pymatgen.io.vasp.inputs — pymatgen 2020.7.3 documentation

# Source code for pymatgen.io.vasp.inputs

    # coding: utf-8
    # Copyright (c) Pymatgen Development Team.
    # Distributed under the terms of the MIT License.

    """
    Classes for reading/manipulating/writing VASP input files. All major VASP input
    files.
    """

    import os
    import re
    import itertools
    import warnings
    import logging
    import math
    import json
    import glob
    import subprocess

    import numpy as np

    from numpy.linalg import det
    from collections import OrderedDict, namedtuple
    from hashlib import md5

    from monty.io import zopen
    from monty.os.path import zpath
    from monty.json import MontyDecoder
    from monty.os import cd
    from monty.serialization import loadfn

    from enum import Enum
    from tabulate import tabulate

    import scipy.constants as const

    from pymatgen import SETTINGS, __version__
    from pymatgen.core.lattice import Lattice
    from pymatgen.core.structure import Structure
    from pymatgen.core.periodic_table import Element, get_el_sp
    from pymatgen.electronic_structure.core import Magmom
    from pymatgen.util.string import str_delimited
    from pymatgen.util.io_utils import clean_lines
    from pymatgen.util.typing import PathLike
    from monty.json import MSONable

    __author__ = "Shyue Ping Ong, Geoffroy Hautier, Rickard Armiento, Vincent L Chevrier, Stephen Dacek"
    __copyright__ = "Copyright 2011, The Materials Project"

    logger = logging.getLogger(__name__)

    class Poscar(MSONable):
        """
        Object for representing the data in a POSCAR or CONTCAR file.
        Please note that this current implementation. Most attributes can be set
        directly.

        .. attribute:: structure

            Associated Structure.

        .. attribute:: comment

            Optional comment string.

        .. attribute:: true_names

            Boolean indication whether Poscar contains actual real names parsed
            from either a POTCAR or the POSCAR itself.

        .. attribute:: selective_dynamics

            Selective dynamics attribute for each site if available. A Nx3 array of
            booleans.

        .. attribute:: velocities

            Velocities for each site (typically read in from a CONTCAR). A Nx3
            array of floats.

        .. attribute:: predictor_corrector

            Predictor corrector coordinates and derivatives for each site; i.e.
            a list of three 1x3 arrays for each site (typically read in from a MD
            CONTCAR).

        .. attribute:: predictor_corrector_preamble

            Predictor corrector preamble contains the predictor-corrector key,
            POTIM, and thermostat parameters that precede the site-specic predictor
            corrector data in MD CONTCAR

        .. attribute:: temperature

            Temperature of velocity Maxwell-Boltzmann initialization. Initialized
            to -1 (MB hasn"t been performed).
        """

        def __init__(
            self,
            structure: Structure,
            comment: str = None,
            selective_dynamics=None,
            true_names: bool = True,
            velocities=None,
            predictor_corrector=None,
            predictor_corrector_preamble=None,
            sort_structure: bool = False,
        ):
            """

            :param structure: Structure object.
            :param comment: Optional comment line for POSCAR. Defaults to unit
                cell formula of structure. Defaults to None.
            :param selective_dynamics: bool values for selective dynamics,
                where N is number of sites. Defaults to None.
            :param true_names: Set to False if the names in the POSCAR are not
                well-defined and ambiguous. This situation arises commonly in
                vasp < 5 where the POSCAR sometimes does not contain element
                symbols. Defaults to True.
            :param velocities: Velocities for the POSCAR. Typically parsed
                in MD runs or can be used to initialize velocities.
            :param predictor_corrector: Predictor corrector for the POSCAR.
                Typically parsed in MD runs.
            :param predictor_corrector_preamble: Preamble to the predictor
                corrector.
            :param sort_structure: Whether to sort structure. Useful if species
                are not grouped properly together.
            """
            if structure.is_ordered:
                site_properties = {}
                if selective_dynamics:
                    site_properties["selective_dynamics"] = selective_dynamics
                if velocities:
                    site_properties["velocities"] = velocities
                if predictor_corrector:
                    site_properties["predictor_corrector"] = predictor_corrector
                structure = Structure.from_sites(structure)
                self.structure = structure.copy(site_properties=site_properties)
                if sort_structure:
                    self.structure = self.structure.get_sorted_structure()
                self.true_names = true_names
                self.comment = structure.formula if comment is None else comment
                self.predictor_corrector_preamble = predictor_corrector_preamble
            else:
                raise ValueError(
                    "Structure with partial occupancies cannot be " "converted into POSCAR!"
                )

            self.temperature = -1

        @property
        def velocities(self):
            """Velocities in Poscar"""
            return self.structure.site_properties.get("velocities")

        @property
        def selective_dynamics(self):
            """Selective dynamics in Poscar"""
            return self.structure.site_properties.get("selective_dynamics")

        @property
        def predictor_corrector(self):
            """Predictor corrector in Poscar"""
            return self.structure.site_properties.get("predictor_corrector")

        @velocities.setter  # type: ignore
        def velocities(self, velocities):
            """Setter for Poscar.velocities"""
            self.structure.add_site_property("velocities", velocities)

        @selective_dynamics.setter  # type: ignore
        def selective_dynamics(self, selective_dynamics):
            """Setter for Poscar.selective_dynamics"""
            self.structure.add_site_property("selective_dynamics", selective_dynamics)

        @predictor_corrector.setter  # type: ignore
        def predictor_corrector(self, predictor_corrector):
            """Setter for Poscar.predictor_corrector"""
            self.structure.add_site_property("predictor_corrector", predictor_corrector)

        @property
        def site_symbols(self):
            """
            Sequence of symbols associated with the Poscar. Similar to 6th line in
            vasp 5+ POSCAR.
            """
            syms = [site.specie.symbol for site in self.structure]
            return [a[0] for a in itertools.groupby(syms)]

        @property
        def natoms(self):
            """
            Sequence of number of sites of each type associated with the Poscar.
            Similar to 7th line in vasp 5+ POSCAR or the 6th line in vasp 4 POSCAR.
            """
            syms = [site.specie.symbol for site in self.structure]
            return [len(tuple(a[1])) for a in itertools.groupby(syms)]

        def __setattr__(self, name, value):
            if name in ("selective_dynamics", "velocities"):
                if value is not None and len(value) > 0:
                    value = np.array(value)
                    dim = value.shape
                    if dim[1] != 3 or dim[0] != len(self.structure):
                        raise ValueError(
                            name + " array must be same length as" + " the structure."
                        )
                    value = value.tolist()
            super().__setattr__(name, value)

        @staticmethod
        def from_file(filename, check_for_POTCAR=True, read_velocities=True):
            """
            Reads a Poscar from a file.

            The code will try its best to determine the elements in the POSCAR in
            the following order:

            1. If check_for_POTCAR is True, the code will try to check if a POTCAR
            is in the same directory as the POSCAR and use elements from that by
            default. (This is the VASP default sequence of priority).
            2. If the input file is Vasp5-like and contains element symbols in the
            6th line, the code will use that if check_for_POTCAR is False or there
            is no POTCAR found.
            3. Failing (2), the code will check if a symbol is provided at the end
            of each coordinate.

            If all else fails, the code will just assign the first n elements in
            increasing atomic number, where n is the number of species, to the
            Poscar. For example, H, He, Li, ....  This will ensure at least a
            unique element is assigned to each site and any analysis that does not
            require specific elemental properties should work fine.

            Args:
                filename (str): File name containing Poscar data.
                check_for_POTCAR (bool): Whether to check if a POTCAR is present
                    in the same directory as the POSCAR. Defaults to True.
                read_velocities (bool): Whether to read or not velocities if they
                    are present in the POSCAR. Default is True.

            Returns:
                Poscar object.
            """
            dirname = os.path.dirname(os.path.abspath(filename))
            names = None
            if check_for_POTCAR:
                potcars = glob.glob(os.path.join(dirname, "*POTCAR*"))
                if potcars:
                    try:
                        potcar = Potcar.from_file(sorted(potcars)[0])
                        names = [sym.split("_")[0] for sym in potcar.symbols]
                        [get_el_sp(n) for n in names]  # ensure valid names
                    except Exception:
                        names = None
            with zopen(filename, "rt") as f:
                return Poscar.from_string(f.read(), names, read_velocities=read_velocities)

        @staticmethod
        def from_string(data, default_names=None, read_velocities=True):
            """
            Reads a Poscar from a string.

            The code will try its best to determine the elements in the POSCAR in
            the following order:

            1. If default_names are supplied and valid, it will use those. Usually,
            default names comes from an external source, such as a POTCAR in the
            same directory.

            2. If there are no valid default names but the input file is Vasp5-like
            and contains element symbols in the 6th line, the code will use that.

            3. Failing (2), the code will check if a symbol is provided at the end
            of each coordinate.

            If all else fails, the code will just assign the first n elements in
            increasing atomic number, where n is the number of species, to the
            Poscar. For example, H, He, Li, ....  This will ensure at least a
            unique element is assigned to each site and any analysis that does not
            require specific elemental properties should work fine.

            Args:
                data (str): String containing Poscar data.
                default_names ([str]): Default symbols for the POSCAR file,
                    usually coming from a POTCAR in the same directory.
                read_velocities (bool): Whether to read or not velocities if they
                    are present in the POSCAR. Default is True.

            Returns:
                Poscar object.
            """
            # "^\s*$" doesn't match lines with no whitespace
            chunks = re.split(r"\n\s*\n", data.rstrip(), flags=re.MULTILINE)
            try:
                if chunks[0] == "":
                    chunks.pop(0)
                    chunks[0] = "\n" + chunks[0]
            except IndexError:
                raise ValueError("Empty POSCAR")

            # Parse positions
            lines = tuple(clean_lines(chunks[0].split("\n"), False))
            comment = lines[0]
            scale = float(lines[1])
            lattice = np.array([[float(i) for i in line.split()] for line in lines[2:5]])
            if scale < 0:
                # In vasp, a negative scale factor is treated as a volume. We need
                # to translate this to a proper lattice vector scaling.
                vol = abs(det(lattice))
                lattice *= (-scale / vol) ** (1 / 3)
            else:
                lattice *= scale

            vasp5_symbols = False
            try:
                natoms = [int(i) for i in lines[5].split()]
                ipos = 6
            except ValueError:
                vasp5_symbols = True
                symbols = lines[5].split()

                """
                Atoms and number of atoms in POSCAR written with vasp appear on
                multiple lines when atoms of the same type are not grouped together
                and more than 20 groups are then defined ...
                Example :
                Cr16 Fe35 Ni2
                   1.00000000000000
                     8.5415010000000002   -0.0077670000000000   -0.0007960000000000
                    -0.0077730000000000    8.5224019999999996    0.0105580000000000
                    -0.0007970000000000    0.0105720000000000    8.5356889999999996
                   Fe   Cr   Fe   Cr   Fe   Cr   Fe   Cr   Fe   Cr   Fe   Cr   Fe   Cr   Fe   Ni   Fe   Cr   Fe   Cr
                   Fe   Ni   Fe   Cr   Fe
                     1   1   2   4   2   1   1   1     2     1     1     1     4     1     1     1     5     3     6     1
                     2   1   3   2   5
                Direct
                  ...
                """
                nlines_symbols = 1
                for nlines_symbols in range(1, 11):
                    try:
                        int(lines[5 + nlines_symbols].split()[0])
                        break
                    except ValueError:
                        pass
                for iline_symbols in range(6, 5 + nlines_symbols):
                    symbols.extend(lines[iline_symbols].split())
                natoms = []
                iline_natoms_start = 5 + nlines_symbols
                for iline_natoms in range(
                    iline_natoms_start, iline_natoms_start + nlines_symbols
                ):
                    natoms.extend([int(i) for i in lines[iline_natoms].split()])
                atomic_symbols = list()
                for i in range(len(natoms)):
                    atomic_symbols.extend([symbols[i]] * natoms[i])
                ipos = 5 + 2 * nlines_symbols

            postype = lines[ipos].split()[0]

            sdynamics = False
            # Selective dynamics
            if postype[0] in "sS":
                sdynamics = True
                ipos += 1
                postype = lines[ipos].split()[0]

            cart = postype[0] in "cCkK"
            nsites = sum(natoms)

            # If default_names is specified (usually coming from a POTCAR), use
            # them. This is in line with Vasp"s parsing order that the POTCAR
            # specified is the default used.
            if default_names:
                try:
                    atomic_symbols = []
                    for i in range(len(natoms)):
                        atomic_symbols.extend([default_names[i]] * natoms[i])
                    vasp5_symbols = True
                except IndexError:
                    pass

            if not vasp5_symbols:
                ind = 3 if not sdynamics else 6
                try:
                    # Check if names are appended at the end of the coordinates.
                    atomic_symbols = [
                        l.split()[ind] for l in lines[ipos + 1: ipos + 1 + nsites]
                    ]
                    # Ensure symbols are valid elements
                    if not all([Element.is_valid_symbol(sym) for sym in atomic_symbols]):
                        raise ValueError("Non-valid symbols detected.")
                    vasp5_symbols = True
                except (ValueError, IndexError):
                    # Defaulting to false names.
                    atomic_symbols = []
                    for i in range(len(natoms)):
                        sym = Element.from_Z(i + 1).symbol
                        atomic_symbols.extend([sym] * natoms[i])
                    warnings.warn(
                        "Elements in POSCAR cannot be determined. "
                        "Defaulting to false names %s." % " ".join(atomic_symbols)
                    )

            # read the atomic coordinates
            coords = []
            selective_dynamics = list() if sdynamics else None
            for i in range(nsites):
                toks = lines[ipos + 1 + i].split()
                crd_scale = scale if cart else 1
                coords.append([float(j) * crd_scale for j in toks[:3]])
                if sdynamics:
                    selective_dynamics.append([tok.upper()[0] == "T" for tok in toks[3:6]])

            struct = Structure(
                lattice,
                atomic_symbols,
                coords,
                to_unit_cell=False,
                validate_proximity=False,
                coords_are_cartesian=cart,
            )

            if read_velocities:
                # Parse velocities if any
                velocities = []
                if len(chunks) > 1:
                    for line in chunks[1].strip().split("\n"):
                        velocities.append([float(tok) for tok in line.split()])

                # Parse the predictor-corrector data
                predictor_corrector = []
                predictor_corrector_preamble = None

                if len(chunks) > 2:
                    lines = chunks[2].strip().split("\n")
                    # There are 3 sets of 3xN Predictor corrector parameters
                    # So can't be stored as a single set of "site_property"

                    # First line in chunk is a key in CONTCAR
                    # Second line is POTIM
                    # Third line is the thermostat parameters
                    predictor_corrector_preamble = (
                        lines[0] + "\n" + lines[1] + "\n" + lines[2]
                    )
                    # Rest is three sets of parameters, each set contains
                    # x, y, z predictor-corrector parameters for every atom in orde
                    lines = lines[3:]
                    for st in range(nsites):
                        d1 = [float(tok) for tok in lines[st].split()]
                        d2 = [float(tok) for tok in lines[st + nsites].split()]
                        d3 = [float(tok) for tok in lines[st + 2 * nsites].split()]
                        predictor_corrector.append([d1, d2, d3])
            else:
                velocities = None
                predictor_corrector = None
                predictor_corrector_preamble = None

            return Poscar(
                struct,
                comment,
                selective_dynamics,
                vasp5_symbols,
                velocities=velocities,
                predictor_corrector=predictor_corrector,
                predictor_corrector_preamble=predictor_corrector_preamble,
            )

        def get_string(self, direct=True, vasp4_compatible=False, significant_figures=6):
            """
            Returns a string to be written as a POSCAR file. By default, site
            symbols are written, which means compatibility is for vasp >= 5.

            Args:
                direct (bool): Whether coordinates are output in direct or
                    cartesian. Defaults to True.
                vasp4_compatible (bool): Set to True to omit site symbols on 6th
                    line to maintain backward vasp 4.x compatibility. Defaults
                    to False.
                significant_figures (int): No. of significant figures to
                    output all quantities. Defaults to 6. Note that positions are
                    output in fixed point, while velocities are output in
                    scientific format.

            Returns:
                String representation of POSCAR.
            """

            # This corrects for VASP really annoying bug of crashing on lattices
            # which have triple product < 0. We will just invert the lattice
            # vectors.
            latt = self.structure.lattice
            if np.linalg.det(latt.matrix) < 0:
                latt = Lattice(-latt.matrix)

            format_str = "{{:.{0}f}}".format(significant_figures)
            lines = [self.comment, "1.0"]
            for v in latt.matrix:
                lines.append(" ".join([format_str.format(c) for c in v]))

            if self.true_names and not vasp4_compatible:
                lines.append(" ".join(self.site_symbols))
            lines.append(" ".join([str(x) for x in self.natoms]))
            if self.selective_dynamics:
                lines.append("Selective dynamics")
            lines.append("direct" if direct else "cartesian")

            selective_dynamics = self.selective_dynamics
            for (i, site) in enumerate(self.structure):
                coords = site.frac_coords if direct else site.coords
                line = " ".join([format_str.format(c) for c in coords])
                if selective_dynamics is not None:
                    sd = ["T" if j else "F" for j in selective_dynamics[i]]
                    line += " %s %s %s" % (sd[0], sd[1], sd[2])
                line += " " + site.species_string
                lines.append(line)

            if self.velocities:
                try:
                    lines.append("")
                    for v in self.velocities:
                        lines.append(" ".join([format_str.format(i) for i in v]))
                except Exception:
                    warnings.warn("Velocities are missing or corrupted.")

            if self.predictor_corrector:
                lines.append("")
                if self.predictor_corrector_preamble:
                    lines.append(self.predictor_corrector_preamble)
                    pred = np.array(self.predictor_corrector)
                    for col in range(3):
                        for z in pred[:, col]:
                            lines.append(" ".join([format_str.format(i) for i in z]))
                else:
                    warnings.warn(
                        "Preamble information missing or corrupt. "
                        "Writing Poscar with no predictor corrector data."
                    )

            return "\n".join(lines) + "\n"

        def __repr__(self):
            return self.get_string()

        def __str__(self):
            """
            String representation of Poscar file.
            """
            return self.get_string()

        def write_file(self, filename, **kwargs):
            """
            Writes POSCAR to a file. The supported kwargs are the same as those for
            the Poscar.get_string method and are passed through directly.
            """
            with zopen(filename, "wt") as f:
                f.write(self.get_string(**kwargs))

        def as_dict(self):
            """
            :return: MSONable dict.
            """
            return {
                "@module": self.__class__.__module__,
                "@class": self.__class__.__name__,
                "structure": self.structure.as_dict(),
                "true_names": self.true_names,
                "selective_dynamics": np.array(self.selective_dynamics).tolist(),
                "velocities": self.velocities,
                "predictor_corrector": self.predictor_corrector,
                "comment": self.comment,
            }

        @classmethod
        def from_dict(cls, d):
            """
            :param d: Dict representation.
            :return: Poscar
            """
            return Poscar(
                Structure.from_dict(d["structure"]),
                comment=d["comment"],
                selective_dynamics=d["selective_dynamics"],
                true_names=d["true_names"],
                velocities=d.get("velocities", None),
                predictor_corrector=d.get("predictor_corrector", None),
            )

        def set_temperature(self, temperature):
            """
            Initializes the velocities based on Maxwell-Boltzmann distribution.
            Removes linear, but not angular drift (same as VASP)

            Scales the energies to the exact temperature (microcanonical ensemble)
            Velocities are given in A/fs. This is the vasp default when
            direct/cartesian is not specified (even when positions are given in
            direct coordinates)

            Overwrites imported velocities, if any.

            Args:
                temperature (float): Temperature in Kelvin.
            """
            # mean 0 variance 1
            velocities = np.random.randn(len(self.structure), 3)

            # in AMU, (N,1) array
            atomic_masses = np.array(
                [site.specie.atomic_mass.to("kg") for site in self.structure]
            )
            dof = 3 * len(self.structure) - 3

            # scale velocities due to atomic masses
            # mean 0 std proportional to sqrt(1/m)
            velocities /= atomic_masses[:, np.newaxis] ** (1 / 2)

            # remove linear drift (net momentum)
            velocities -= np.average(
                atomic_masses[:, np.newaxis] * velocities, axis=0
            ) / np.average(atomic_masses)

            # scale velocities to get correct temperature
            energy = np.sum(1 / 2 * atomic_masses * np.sum(velocities ** 2, axis=1))
            scale = (temperature * dof / (2 * energy / const.k)) ** (1 / 2)

            velocities *= scale * 1e-5  # these are in A/fs

            self.temperature = temperature
            try:
                del self.structure.site_properties["selective_dynamics"]
            except KeyError:
                pass

            try:
                del self.structure.site_properties["predictor_corrector"]
            except KeyError:
                pass
            # returns as a list of lists to be consistent with the other
            # initializations

            self.structure.add_site_property("velocities", velocities.tolist())

    cwd = os.path.abspath(os.path.dirname(__file__))
    with open(os.path.join(cwd, "incar_parameters.json")) as incar_params:
        incar_params = json.loads(incar_params.read())

    class BadIncarWarning(UserWarning):
        """
        Warning class for bad Incar parameters.
        """

        pass

    class Incar(dict, MSONable):
        """
        INCAR object for reading and writing INCAR files. Essentially consists of
        a dictionary with some helper functions
        """

        def __init__(self, params=None):
            """
            Creates an Incar object.

            Args:
                params (dict): A set of input parameters as a dictionary.
            """
            super().__init__()
            if params:

                # if Incar contains vector-like magmoms given as a list
                # of floats, convert to a list of lists
                if (
                    params.get("MAGMOM") and isinstance(params["MAGMOM"][0], (int, float))
                ) and (params.get("LSORBIT") or params.get("LNONCOLLINEAR")):
                    val = []
                    for i in range(len(params["MAGMOM"]) // 3):
                        val.append(params["MAGMOM"][i * 3: (i + 1) * 3])
                    params["MAGMOM"] = val

                self.update(params)

        def __setitem__(self, key, val):
            """
            Add parameter-val pair to Incar.  Warns if parameter is not in list of
            valid INCAR tags. Also cleans the parameter and val by stripping
            leading and trailing white spaces.
            """
            super().__setitem__(
                key.strip(),
                Incar.proc_val(key.strip(), val.strip()) if isinstance(val, str) else val,
            )

        def as_dict(self):
            """
            :return: MSONable dict.
            """
            d = dict(self)
            d["@module"] = self.__class__.__module__
            d["@class"] = self.__class__.__name__
            return d

        @classmethod
        def from_dict(cls, d):
            """
            :param d: Dict representation.
            :return: Incar
            """
            if d.get("MAGMOM") and isinstance(d["MAGMOM"][0], dict):
                d["MAGMOM"] = [Magmom.from_dict(m) for m in d["MAGMOM"]]
            return Incar({k: v for k, v in d.items() if k not in ("@module", "@class")})

        def get_string(self, sort_keys=False, pretty=False):
            """
            Returns a string representation of the INCAR.  The reason why this
            method is different from the __str__ method is to provide options for
            pretty printing.

            Args:
                sort_keys (bool): Set to True to sort the INCAR parameters
                    alphabetically. Defaults to False.
                pretty (bool): Set to True for pretty aligned output. Defaults
                    to False.
            """
            keys = self.keys()
            if sort_keys:
                keys = sorted(keys)
            lines = []
            for k in keys:
                if k == "MAGMOM" and isinstance(self[k], list):
                    value = []

                    if (
                        isinstance(self[k][0], list) or isinstance(self[k][0], Magmom)
                    ) and (self.get("LSORBIT") or self.get("LNONCOLLINEAR")):
                        value.append(" ".join(str(i) for j in self[k] for i in j))
                    elif self.get("LSORBIT") or self.get("LNONCOLLINEAR"):
                        for m, g in itertools.groupby(self[k]):
                            value.append("3*{}*{}".format(len(tuple(g)), m))
                    else:
                        # float() to ensure backwards compatibility between
                        # float magmoms and Magmom objects
                        for m, g in itertools.groupby(self[k], lambda x: float(x)):
                            value.append("{}*{}".format(len(tuple(g)), m))

                    lines.append([k, " ".join(value)])
                elif isinstance(self[k], list):
                    lines.append([k, " ".join([str(i) for i in self[k]])])
                else:
                    lines.append([k, self[k]])

            if pretty:
                return str(tabulate([[l[0], "=", l[1]] for l in lines], tablefmt="plain"))
            else:
                return str_delimited(lines, None, " = ") + "\n"

        def __str__(self):
            return self.get_string(sort_keys=True, pretty=False)

        def write_file(self, filename):
            """
            Write Incar to a file.

            Args:
                filename (str): filename to write to.
            """
            with zopen(filename, "wt") as f:
                f.write(self.__str__())

        @staticmethod
        def from_file(filename):
            """
            Reads an Incar object from a file.

            Args:
                filename (str): Filename for file

            Returns:
                Incar object
            """
            with zopen(filename, "rt") as f:
                return Incar.from_string(f.read())

        @staticmethod
        def from_string(string):
            """
            Reads an Incar object from a string.

            Args:
                string (str): Incar string

            Returns:
                Incar object
            """
            lines = list(clean_lines(string.splitlines()))
            params = {}
            for line in lines:
                for sline in line.split(";"):
                    m = re.match(r"(\w+)\s*=\s*(.*)", sline.strip())
                    if m:
                        key = m.group(1).strip()
                        val = m.group(2).strip()
                        val = Incar.proc_val(key, val)
                        params[key] = val
            return Incar(params)

        @staticmethod
        def proc_val(key, val):
            """
            Static helper method to convert INCAR parameters to proper types, e.g.,
            integers, floats, lists, etc.

            Args:
                key: INCAR parameter key
                val: Actual value of INCAR parameter.
            """
            list_keys = (
                "LDAUU",
                "LDAUL",
                "LDAUJ",
                "MAGMOM",
                "DIPOL",
                "LANGEVIN_GAMMA",
                "QUAD_EFG",
                "EINT",
            )
            bool_keys = (
                "LDAU",
                "LWAVE",
                "LSCALU",
                "LCHARG",
                "LPLANE",
                "LUSE_VDW",
                "LHFCALC",
                "ADDGRID",
                "LSORBIT",
                "LNONCOLLINEAR",
            )
            float_keys = (
                "EDIFF",
                "SIGMA",
                "TIME",
                "ENCUTFOCK",
                "HFSCREEN",
                "POTIM",
                "EDIFFG",
                "AGGAC",
                "PARAM1",
                "PARAM2",
            )
            int_keys = (
                "NSW",
                "NBANDS",
                "NELMIN",
                "ISIF",
                "IBRION",
                "ISPIN",
                "ICHARG",
                "NELM",
                "ISMEAR",
                "NPAR",
                "LDAUPRINT",
                "LMAXMIX",
                "ENCUT",
                "NSIM",
                "NKRED",
                "NUPDOWN",
                "ISPIND",
                "LDAUTYPE",
                "IVDW",
            )

            def smart_int_or_float(numstr):
                if numstr.find(".") != -1 or numstr.lower().find("e") != -1:
                    return float(numstr)
                else:
                    return int(numstr)

            try:
                if key in list_keys:
                    output = []
                    toks = re.findall(
                        r"(-?\d+\.?\d*)\*?(-?\d+\.?\d*)?\*?(-?\d+\.?\d*)?", val
                    )
                    for tok in toks:
                        if tok[2] and "3" in tok[0]:
                            output.extend(
                                [smart_int_or_float(tok[2])] * int(tok[0]) * int(tok[1])
                            )
                        elif tok[1]:
                            output.extend([smart_int_or_float(tok[1])] * int(tok[0]))
                        else:
                            output.append(smart_int_or_float(tok[0]))
                    return output
                if key in bool_keys:
                    m = re.match(r"^\.?([T|F|t|f])[A-Za-z]*\.?", val)
                    if m:
                        if m.group(1) == "T" or m.group(1) == "t":
                            return True
                        else:
                            return False
                    raise ValueError(key + " should be a boolean type!")

                if key in float_keys:
                    return float(re.search(r"^-?\d*\.?\d*[e|E]?-?\d*", val).group(0))

                if key in int_keys:
                    return int(re.match(r"^-?[0-9]+", val).group(0))

            except ValueError:
                pass

            # Not in standard keys. We will try a hierarchy of conversions.
            try:
                val = int(val)
                return val
            except ValueError:
                pass

            try:
                val = float(val)
                return val
            except ValueError:
                pass

            if "true" in val.lower():
                return True

            if "false" in val.lower():
                return False

            return val.strip().capitalize()

        def diff(self, other):
            """
            Diff function for Incar.  Compares two Incars and indicates which
            parameters are the same and which are not. Useful for checking whether
            two runs were done using the same parameters.

            Args:
                other (Incar): The other Incar object to compare to.

            Returns:
                Dict of the following format:
                {"Same" : parameters_that_are_the_same,
                "Different": parameters_that_are_different}
                Note that the parameters are return as full dictionaries of values.
                E.g. {"ISIF":3}
            """
            similar_param = {}
            different_param = {}
            for k1, v1 in self.items():
                if k1 not in other:
                    different_param[k1] = {"INCAR1": v1, "INCAR2": None}
                elif v1 != other[k1]:
                    different_param[k1] = {"INCAR1": v1, "INCAR2": other[k1]}
                else:
                    similar_param[k1] = v1
            for k2, v2 in other.items():
                if k2 not in similar_param and k2 not in different_param:
                    if k2 not in self:
                        different_param[k2] = {"INCAR1": None, "INCAR2": v2}
            return {"Same": similar_param, "Different": different_param}

        def __add__(self, other):
            """
            Add all the values of another INCAR object to this object.
            Facilitates the use of "standard" INCARs.
            """
            params = {k: v for k, v in self.items()}
            for k, v in other.items():
                if k in self and v != self[k]:
                    raise ValueError("Incars have conflicting values!")
                else:
                    params[k] = v
            return Incar(params)

        def check_params(self):
            """
            Raises a warning for nonsensical or non-existant INCAR tags and
            parameters. If a keyword doesn't exist (e.g. theres a typo in a
            keyword), your calculation will still run, however VASP will igore the
            parameter without letting you know, hence why we have this Incar method.
            """
            for k in self.keys():

                # First check if this parameter even exists
                if k not in incar_params.keys():
                    warnings.warn(
                        "Cannot find %s in the list of INCAR flags" % (k),
                        BadIncarWarning,
                        stacklevel=2,
                    )

                if k in incar_params.keys():
                    if type(incar_params[k]).__name__ == "str":
                        # Now we check if this is an appropriate parameter type
                        if incar_params[k] == "float":
                            if not type(self[k]) not in ["float", "int"]:
                                warnings.warn(
                                    "%s: %s is not real" % (k, self[k]),
                                    BadIncarWarning,
                                    stacklevel=2,
                                )
                        elif type(self[k]).__name__ != incar_params[k]:
                            warnings.warn(
                                "%s: %s is not a %s" % (k, self[k], incar_params[k]),
                                BadIncarWarning,
                                stacklevel=2,
                            )

                    # if we have a list of possible parameters, check
                    # if the user given parameter is in this list
                    elif type(incar_params[k]).__name__ == "list":
                        if self[k] not in incar_params[k]:
                            warnings.warn(
                                "%s: Cannot find %s in the list of parameters"
                                % (k, self[k]),
                                BadIncarWarning,
                                stacklevel=2,
                            )

    class Kpoints_supported_modes(Enum):
        """
        Enum type of all supported modes for Kpoint generation.
        """

        Automatic = 0
        Gamma = 1
        Monkhorst = 2
        Line_mode = 3
        Cartesian = 4
        Reciprocal = 5

        def __str__(self):
            return self.name

        @staticmethod
        def from_string(s: str) -> "Kpoints_supported_modes":
            """
            :param s: String
            :return: Kpoints_supported_modes
            """
            c = s.lower()[0]
            for m in Kpoints_supported_modes:
                if m.name.lower()[0] == c:
                    return m
            raise ValueError("Can't interprete Kpoint mode %s" % s)

    class Kpoints(MSONable):
        """
        KPOINT reader/writer.
        """

        supported_modes = Kpoints_supported_modes

        def __init__(
            self,
            comment="Default gamma",
            num_kpts=0,
            style=supported_modes.Gamma,
            kpts=((1, 1, 1),),
            kpts_shift=(0, 0, 0),
            kpts_weights=None,
            coord_type=None,
            labels=None,
            tet_number=0,
            tet_weight=0,
            tet_connections=None,
        ):
            """
            Highly flexible constructor for Kpoints object.  The flexibility comes
            at the cost of usability and in general, it is recommended that you use
            the default constructor only if you know exactly what you are doing and
            requires the flexibility.  For most usage cases, the three automatic
            schemes can be constructed far more easily using the convenience static
            constructors (automatic, gamma_automatic, monkhorst_automatic) and it
            is recommended that you use those.

            Args:
                comment (str): String comment for Kpoints
                num_kpts: Following VASP method of defining the KPOINTS file, this
                    parameter is the number of kpoints specified. If set to 0
                    (or negative), VASP automatically generates the KPOINTS.
                style: Style for generating KPOINTS.  Use one of the
                    Kpoints.supported_modes enum types.
                kpts (2D array): 2D array of kpoints.  Even when only a single
                    specification is required, e.g. in the automatic scheme,
                    the kpts should still be specified as a 2D array. e.g.,
                    [[20]] or [[2,2,2]].
                kpts_shift (3x1 array): Shift for Kpoints.
                kpts_weights: Optional weights for kpoints.  Weights should be
                    integers. For explicit kpoints.
                coord_type: In line-mode, this variable specifies whether the
                    Kpoints were given in Cartesian or Reciprocal coordinates.
                labels: In line-mode, this should provide a list of labels for
                    each kpt. It is optional in explicit kpoint mode as comments for
                    k-points.
                tet_number: For explicit kpoints, specifies the number of
                    tetrahedrons for the tetrahedron method.
                tet_weight: For explicit kpoints, specifies the weight for each
                    tetrahedron for the tetrahedron method.
                tet_connections: For explicit kpoints, specifies the connections
                    of the tetrahedrons for the tetrahedron method.
                    Format is a list of tuples, [ (sym_weight, [tet_vertices]),
                    ...]

            The default behavior of the constructor is for a Gamma centered,
            1x1x1 KPOINTS with no shift.
            """
            if num_kpts > 0 and (not labels) and (not kpts_weights):
                raise ValueError(
                    "For explicit or line-mode kpoints, either the "
                    "labels or kpts_weights must be specified."
                )

            self.comment = comment
            self.num_kpts = num_kpts
            self.kpts = kpts
            self.style = style
            self.coord_type = coord_type
            self.kpts_weights = kpts_weights
            self.kpts_shift = kpts_shift
            self.labels = labels
            self.tet_number = tet_number
            self.tet_weight = tet_weight
            self.tet_connections = tet_connections

        @property
        def style(self):
            """
            :return: Style for kpoint generation. One of Kpoints_supported_modes
                enum.
            """
            return self._style

        @style.setter
        def style(self, style):
            """
            :param style: Style
            :return: Sets the style for the Kpoints. One of Kpoints_supported_modes
                enum.
            """
            if isinstance(style, str):
                style = Kpoints.supported_modes.from_string(style)

            if (
                style
                in (
                    Kpoints.supported_modes.Automatic,
                    Kpoints.supported_modes.Gamma,
                    Kpoints.supported_modes.Monkhorst,
                )
                and len(self.kpts) > 1
            ):
                raise ValueError(
                    "For fully automatic or automatic gamma or monk "
                    "kpoints, only a single line for the number of "
                    "divisions is allowed."
                )

            self._style = style

        @staticmethod
        def automatic(subdivisions):
            """
            Convenient static constructor for a fully automatic Kpoint grid, with
            gamma centered Monkhorst-Pack grids and the number of subdivisions
            along each reciprocal lattice vector determined by the scheme in the
            VASP manual.

            Args:
                subdivisions: Parameter determining number of subdivisions along
                    each reciprocal lattice vector.

            Returns:
                Kpoints object
            """
            return Kpoints(
                "Fully automatic kpoint scheme",
                0,
                style=Kpoints.supported_modes.Automatic,
                kpts=[[subdivisions]],
            )

        @staticmethod
        def gamma_automatic(kpts=(1, 1, 1), shift=(0, 0, 0)):
            """
            Convenient static constructor for an automatic Gamma centered Kpoint
            grid.

            Args:
                kpts: Subdivisions N_1, N_2 and N_3 along reciprocal lattice
                    vectors. Defaults to (1,1,1)
                shift: Shift to be applied to the kpoints. Defaults to (0,0,0).

            Returns:
                Kpoints object
            """
            return Kpoints(
                "Automatic kpoint scheme",
                0,
                Kpoints.supported_modes.Gamma,
                kpts=[kpts],
                kpts_shift=shift,
            )

        @staticmethod
        def monkhorst_automatic(kpts=(2, 2, 2), shift=(0, 0, 0)):
            """
            Convenient static constructor for an automatic Monkhorst pack Kpoint
            grid.

            Args:
                kpts: Subdivisions N_1, N_2 and N_3 along reciprocal lattice
                    vectors. Defaults to (2,2,2)
                shift: Shift to be applied to the kpoints. Defaults to (0,0,0).

            Returns:
                Kpoints object
            """
            return Kpoints(
                "Automatic kpoint scheme",
                0,
                Kpoints.supported_modes.Monkhorst,
                kpts=[kpts],
                kpts_shift=shift,
            )

        @staticmethod
        def automatic_density(structure, kppa, force_gamma=False):
            """
            Returns an automatic Kpoint object based on a structure and a kpoint
            density. Uses Gamma centered meshes for hexagonal cells and
            Monkhorst-Pack grids otherwise.

            Algorithm:
                Uses a simple approach scaling the number of divisions along each
                reciprocal lattice vector proportional to its length.

            Args:
                structure (Structure): Input structure
                kppa (int): Grid density
                force_gamma (bool): Force a gamma centered mesh (default is to
                    use gamma only for hexagonal cells or odd meshes)

            Returns:
                Kpoints
            """
            comment = "pymatgen v%s with grid density = %.0f / number of atoms" % (__version__, kppa)
            if math.fabs((math.floor(kppa ** (1 / 3) + 0.5)) ** 3 - kppa) < 1:
                kppa += kppa * 0.01
            latt = structure.lattice
            lengths = latt.abc
            ngrid = kppa / structure.num_sites
            mult = (ngrid * lengths[0] * lengths[1] * lengths[2]) ** (1 / 3)

            num_div = [int(math.floor(max(mult / l, 1))) for l in lengths]

            is_hexagonal = latt.is_hexagonal()

            has_odd = any([i % 2 == 1 for i in num_div])
            if has_odd or is_hexagonal or force_gamma:
                style = Kpoints.supported_modes.Gamma
            else:
                style = Kpoints.supported_modes.Monkhorst

            return Kpoints(comment, 0, style, [num_div], [0, 0, 0])

        @staticmethod
        def automatic_gamma_density(structure, kppa):
            """
            Returns an automatic Kpoint object based on a structure and a kpoint
            density. Uses Gamma centered meshes always. For GW.

            Algorithm:
                Uses a simple approach scaling the number of divisions along each
                reciprocal lattice vector proportional to its length.

            Args:
                structure:
                    Input structure
                kppa:
                    Grid density
            """

            latt = structure.lattice
            lengths = latt.abc
            ngrid = kppa / structure.num_sites

            mult = (ngrid * lengths[0] * lengths[1] * lengths[2]) ** (1 / 3)
            num_div = [int(round(mult / l)) for l in lengths]

            # ensure that numDiv[i] > 0
            num_div = [i if i > 0 else 1 for i in num_div]

            # VASP documentation recommends to use even grids for n <= 8 and odd
            # grids for n > 8.
            num_div = [i + i % 2 if i <= 8 else i - i % 2 + 1 for i in num_div]

            style = Kpoints.supported_modes.Gamma

            comment = "pymatgen v%s with grid density = %.0f / number of atoms" % (__version__, kppa)

            num_kpts = 0
            return Kpoints(comment, num_kpts, style, [num_div], [0, 0, 0])

        @staticmethod
        def automatic_density_by_vol(structure, kppvol, force_gamma=False):
            """
            Returns an automatic Kpoint object based on a structure and a kpoint
            density per inverse Angstrom^3 of reciprocal cell.

            Algorithm:
                Same as automatic_density()

            Args:
                structure (Structure): Input structure
                kppvol (int): Grid density per Angstrom^(-3) of reciprocal cell
                force_gamma (bool): Force a gamma centered mesh

            Returns:
                Kpoints
            """
            vol = structure.lattice.reciprocal_lattice.volume
            kppa = kppvol * vol * structure.num_sites
            return Kpoints.automatic_density(structure, kppa, force_gamma=force_gamma)

        @staticmethod
        def automatic_linemode(divisions, ibz):
            """
            Convenient static constructor for a KPOINTS in mode line_mode.
            gamma centered Monkhorst-Pack grids and the number of subdivisions
            along each reciprocal lattice vector determined by the scheme in the
            VASP manual.

            Args:
                divisions: Parameter determining the number of k-points along each
                    hight symetry lines.
                ibz: HighSymmKpath object (pymatgen.symmetry.bandstructure)

            Returns:
                Kpoints object
            """
            kpoints = list()
            labels = list()
            for path in ibz.kpath["path"]:
                kpoints.append(ibz.kpath["kpoints"][path[0]])
                labels.append(path[0])
                for i in range(1, len(path) - 1):
                    kpoints.append(ibz.kpath["kpoints"][path[i]])
                    labels.append(path[i])
                    kpoints.append(ibz.kpath["kpoints"][path[i]])
                    labels.append(path[i])

                kpoints.append(ibz.kpath["kpoints"][path[-1]])
                labels.append(path[-1])

            return Kpoints(
                "Line_mode KPOINTS file",
                style=Kpoints.supported_modes.Line_mode,
                coord_type="Reciprocal",
                kpts=kpoints,
                labels=labels,
                num_kpts=int(divisions),
            )

        @staticmethod
        def from_file(filename):
            """
            Reads a Kpoints object from a KPOINTS file.

            Args:
                filename (str): filename to read from.

            Returns:
                Kpoints object
            """
            with zopen(filename, "rt") as f:
                return Kpoints.from_string(f.read())

        @staticmethod
        def from_string(string):
            """
            Reads a Kpoints object from a KPOINTS string.

            Args:
                string (str): KPOINTS string.

            Returns:
                Kpoints object
            """
            lines = [line.strip() for line in string.splitlines()]

            comment = lines[0]
            num_kpts = int(lines[1].split()[0].strip())
            style = lines[2].lower()[0]

            # Fully automatic KPOINTS
            if style == "a":
                return Kpoints.automatic(int(lines[3]))

            coord_pattern = re.compile(
                r"^\s*([\d+.\-Ee]+)\s+([\d+.\-Ee]+)\s+" r"([\d+.\-Ee]+)"
            )

            # Automatic gamma and Monk KPOINTS, with optional shift
            if style == "g" or style == "m":
                kpts = [int(i) for i in lines[3].split()]
                kpts_shift = (0, 0, 0)
                if len(lines) > 4 and coord_pattern.match(lines[4]):
                    try:
                        kpts_shift = [float(i) for i in lines[4].split()]
                    except ValueError:
                        pass
                return (
                    Kpoints.gamma_automatic(kpts, kpts_shift)
                    if style == "g"
                    else Kpoints.monkhorst_automatic(kpts, kpts_shift)
                )

            # Automatic kpoints with basis
            if num_kpts <= 0:
                style = (
                    Kpoints.supported_modes.Cartesian
                    if style in "ck"
                    else Kpoints.supported_modes.Reciprocal
                )
                kpts = [[float(j) for j in lines[i].split()] for i in range(3, 6)]
                kpts_shift = [float(i) for i in lines[6].split()]
                return Kpoints(
                    comment=comment,
                    num_kpts=num_kpts,
                    style=style,
                    kpts=kpts,
                    kpts_shift=kpts_shift,
                )

            # Line-mode KPOINTS, usually used with band structures
            if style == "l":
                coord_type = "Cartesian" if lines[3].lower()[0] in "ck" else "Reciprocal"
                style = Kpoints.supported_modes.Line_mode
                kpts = []
                labels = []
                patt = re.compile(
                    r"([e0-9.\-]+)\s+([e0-9.\-]+)\s+([e0-9.\-]+)" r"\s*!*\s*(.*)"
                )
                for i in range(4, len(lines)):
                    line = lines[i]
                    m = patt.match(line)
                    if m:
                        kpts.append(
                            [float(m.group(1)), float(m.group(2)), float(m.group(3))]
                        )
                        labels.append(m.group(4).strip())
                return Kpoints(
                    comment=comment,
                    num_kpts=num_kpts,
                    style=style,
                    kpts=kpts,
                    coord_type=coord_type,
                    labels=labels,
                )

            # Assume explicit KPOINTS if all else fails.
            style = (
                Kpoints.supported_modes.Cartesian
                if style in "ck"
                else Kpoints.supported_modes.Reciprocal
            )
            kpts = []
            kpts_weights = []
            labels = []
            tet_number = 0
            tet_weight = 0
            tet_connections = None

            for i in range(3, 3 + num_kpts):
                toks = lines[i].split()
                kpts.append([float(j) for j in toks[0:3]])
                kpts_weights.append(float(toks[3]))
                if len(toks) > 4:
                    labels.append(toks[4])
                else:
                    labels.append(None)
            try:
                # Deal with tetrahedron method
                if lines[3 + num_kpts].strip().lower()[0] == "t":
                    toks = lines[4 + num_kpts].split()
                    tet_number = int(toks[0])
                    tet_weight = float(toks[1])
                    tet_connections = []
                    for i in range(5 + num_kpts, 5 + num_kpts + tet_number):
                        toks = lines[i].split()
                        tet_connections.append(
                            (int(toks[0]), [int(toks[j]) for j in range(1, 5)])
                        )
            except IndexError:
                pass

            return Kpoints(
                comment=comment,
                num_kpts=num_kpts,
                style=Kpoints.supported_modes[str(style)],
                kpts=kpts,
                kpts_weights=kpts_weights,
                tet_number=tet_number,
                tet_weight=tet_weight,
                tet_connections=tet_connections,
                labels=labels,
            )

        def write_file(self, filename):
            """
            Write Kpoints to a file.

            Args:
                filename (str): Filename to write to.
            """
            with zopen(filename, "wt") as f:
                f.write(self.__str__())

        def __repr__(self):
            return self.__str__()

        def __str__(self):
            lines = [self.comment, str(self.num_kpts), self.style.name]
            style = self.style.name.lower()[0]
            if style == "l":
                lines.append(self.coord_type)
            for i in range(len(self.kpts)):
                lines.append(" ".join([str(x) for x in self.kpts[i]]))
                if style == "l":
                    lines[-1] += " ! " + self.labels[i]
                    if i % 2 == 1:
                        lines[-1] += "\n"
                elif self.num_kpts > 0:
                    if self.labels is not None:
                        lines[-1] += " %i %s" % (self.kpts_weights[i], self.labels[i])
                    else:
                        lines[-1] += " %i" % (self.kpts_weights[i])

            # Print tetrahedron parameters if the number of tetrahedrons > 0
            if style not in "lagm" and self.tet_number > 0:
                lines.append("Tetrahedron")
                lines.append("%d %f" % (self.tet_number, self.tet_weight))
                for sym_weight, vertices in self.tet_connections:
                    lines.append(
                        "%d %d %d %d %d"
                        % (sym_weight, vertices[0], vertices[1], vertices[2], vertices[3])
                    )

            # Print shifts for automatic kpoints types if not zero.
            if self.num_kpts <= 0 and tuple(self.kpts_shift) != (0, 0, 0):
                lines.append(" ".join([str(x) for x in self.kpts_shift]))
            return "\n".join(lines) + "\n"

        def as_dict(self):
            """
            :return: MSONable dict.
            """
            d = {
                "comment": self.comment,
                "nkpoints": self.num_kpts,
                "generation_style": self.style.name,
                "kpoints": self.kpts,
                "usershift": self.kpts_shift,
                "kpts_weights": self.kpts_weights,
                "coord_type": self.coord_type,
                "labels": self.labels,
                "tet_number": self.tet_number,
                "tet_weight": self.tet_weight,
                "tet_connections": self.tet_connections,
            }

            optional_paras = ["genvec1", "genvec2", "genvec3", "shift"]
            for para in optional_paras:
                if para in self.__dict__:
                    d[para] = self.__dict__[para]
            d["@module"] = self.__class__.__module__
            d["@class"] = self.__class__.__name__
            return d

        @classmethod
        def from_dict(cls, d):
            """
            :param d: Dict representation.
            :return: Kpoints
            """
            comment = d.get("comment", "")
            generation_style = d.get("generation_style")
            kpts = d.get("kpoints", [[1, 1, 1]])
            kpts_shift = d.get("usershift", [0, 0, 0])
            num_kpts = d.get("nkpoints", 0)
            return cls(
                comment=comment,
                kpts=kpts,
                style=generation_style,
                kpts_shift=kpts_shift,
                num_kpts=num_kpts,
                kpts_weights=d.get("kpts_weights"),
                coord_type=d.get("coord_type"),
                labels=d.get("labels"),
                tet_number=d.get("tet_number", 0),
                tet_weight=d.get("tet_weight", 0),
                tet_connections=d.get("tet_connections"),
            )

    def _parse_string(s):
        return "{}".format(s.strip())

    def _parse_bool(s):
        m = re.match(r"^\.?([TFtf])[A-Za-z]*\.?", s)
        if m:
            if m.group(1) == "T" or m.group(1) == "t":
                return True
            else:
                return False
        raise ValueError(s + " should be a boolean type!")

    def _parse_float(s):
        return float(re.search(r"^-?\d*\.?\d*[eE]?-?\d*", s).group(0))

    def _parse_int(s):
        return int(re.match(r"^-?[0-9]+", s).group(0))

    def _parse_list(s):
        return [float(y) for y in re.split(r"\s+", s.strip()) if not y.isalpha()]

    Orbital = namedtuple("Orbital", ["n", "l", "j", "E", "occ"])
    OrbitalDescription = namedtuple(
        "OrbitalDescription", ["l", "E", "Type", "Rcut", "Type2", "Rcut2"]
    )

    class UnknownPotcarWarning(UserWarning):
        """
        Warning raised when POTCAR hashes do not pass validation
        """

        pass

    class PotcarSingle:
        """
        Object for a **single** POTCAR. The builder assumes the POTCAR contains
        the complete untouched data in "data" as a string and a dict of keywords.

        .. attribute:: data

            POTCAR data as a string.

        .. attribute:: keywords

            Keywords parsed from the POTCAR as a dict. All keywords are also
            accessible as attributes in themselves. E.g., potcar.enmax,
            potcar.encut, etc.

        md5 hashes of the entire POTCAR file and the actual data are validated
        against a database of known good hashes. Appropriate warnings or errors
        are raised if a POTCAR hash fails validation.
        """

        functional_dir = {
            "PBE": "POT_GGA_PAW_PBE",
            "PBE_52": "POT_GGA_PAW_PBE_52",
            "PBE_54": "POT_GGA_PAW_PBE_54",
            "LDA": "POT_LDA_PAW",
            "LDA_52": "POT_LDA_PAW_52",
            "LDA_54": "POT_LDA_PAW_54",
            "PW91": "POT_GGA_PAW_PW91",
            "LDA_US": "POT_LDA_US",
            "PW91_US": "POT_GGA_US_PW91",
            "Perdew-Zunger81": "POT_LDA_PAW",
        }

        functional_tags = {
            "pe": {"name": "PBE", "class": "GGA"},
            "91": {"name": "PW91", "class": "GGA"},
            "rp": {"name": "revPBE", "class": "GGA"},
            "am": {"name": "AM05", "class": "GGA"},
            "ps": {"name": "PBEsol", "class": "GGA"},
            "pw": {"name": "PW86", "class": "GGA"},
            "lm": {"name": "Langreth-Mehl-Hu", "class": "GGA"},
            "pb": {"name": "Perdew-Becke", "class": "GGA"},
            "ca": {"name": "Perdew-Zunger81", "class": "LDA"},
            "hl": {"name": "Hedin-Lundquist", "class": "LDA"},
            "wi": {"name": "Wigner Interpoloation", "class": "LDA"},
        }

        parse_functions = {
            "LULTRA": _parse_bool,
            "LUNSCR": _parse_bool,
            "LCOR": _parse_bool,
            "LPAW": _parse_bool,
            "EATOM": _parse_float,
            "RPACOR": _parse_float,
            "POMASS": _parse_float,
            "ZVAL": _parse_float,
            "RCORE": _parse_float,
            "RWIGS": _parse_float,
            "ENMAX": _parse_float,
            "ENMIN": _parse_float,
            "EMMIN": _parse_float,
            "EAUG": _parse_float,
            "DEXC": _parse_float,
            "RMAX": _parse_float,
            "RAUG": _parse_float,
            "RDEP": _parse_float,
            "RDEPT": _parse_float,
            "QCUT": _parse_float,
            "QGAM": _parse_float,
            "RCLOC": _parse_float,
            "IUNSCR": _parse_int,
            "ICORE": _parse_int,
            "NDATA": _parse_int,
            "VRHFIN": _parse_string,
            "LEXCH": _parse_string,
            "TITEL": _parse_string,
            "STEP": _parse_list,
            "RRKJ": _parse_list,
            "GGA": _parse_list,
        }

        def __init__(self, data, symbol=None):
            """
            Args:
                data:
                    Complete and single potcar file as a string.
                symbol:
                    POTCAR symbol corresponding to the filename suffix
                    e.g. "Tm_3" for POTCAR.TM_3". If not given, pymatgen
                    will attempt to extract the symbol from the file itself.
                    However, this is not always reliable!
            """
            self.data = data  # raw POTCAR as a string

            # Vasp parses header in vasprun.xml and this differs from the titel
            self.header = data.split("\n")[0].strip()

            search_lines = re.search(
                r"(?s)(parameters from PSCTR are:" r".*?END of PSCTR-controll parameters)",
                data,
            ).group(1)

            self.keywords = {}
            for key, val in re.findall(
                r"(\S+)\s*=\s*(.*?)(?=;|$)", search_lines, flags=re.MULTILINE
            ):
                try:
                    self.keywords[key] = self.parse_functions[key](val)
                except KeyError:
                    warnings.warn("Ignoring unknown variable type %s" % key)

            PSCTR = OrderedDict()

            array_search = re.compile(r"(-*[0-9.]+)")
            orbitals = []
            descriptions = []
            atomic_configuration = re.search(
                r"Atomic configuration\s*\n?" r"(.*?)Description", search_lines
            )
            if atomic_configuration:
                lines = atomic_configuration.group(1).splitlines()
                num_entries = re.search(r"([0-9]+)", lines[0]).group(1)
                num_entries = int(num_entries)
                PSCTR["nentries"] = num_entries
                for line in lines[1:]:
                    orbit = array_search.findall(line)
                    if orbit:
                        orbitals.append(
                            self.Orbital(
                                int(orbit[0]),
                                int(orbit[1]),
                                float(orbit[2]),
                                float(orbit[3]),
                                float(orbit[4]),
                            )
                        )
                PSCTR["Orbitals"] = tuple(orbitals)

            description_string = re.search(
                r"(?s)Description\s*\n"
                r"(.*?)Error from kinetic"
                r" energy argument \(eV\)",
                search_lines,
            )
            if description_string:
                for line in description_string.group(1).splitlines():
                    description = array_search.findall(line)
                    if description:
                        descriptions.append(
                            OrbitalDescription(
                                int(description[0]),
                                float(description[1]),
                                int(description[2]),
                                float(description[3]),
                                int(description[4]) if len(description) > 4 else None,
                                float(description[5]) if len(description) > 4 else None,
                            )
                        )

            if descriptions:
                PSCTR["OrbitalDescriptions"] = tuple(descriptions)

            rrkj_kinetic_energy_string = re.search(
                r"(?s)Error from kinetic energy argument \(eV\)\s*\n"
                r"(.*?)END of PSCTR-controll parameters",
                search_lines,
            )
            rrkj_array = []
            if rrkj_kinetic_energy_string:
                for line in rrkj_kinetic_energy_string.group(1).splitlines():
                    if "=" not in line:
                        rrkj_array += _parse_list(line.strip("\n"))
                if rrkj_array:
                    PSCTR["RRKJ"] = tuple(rrkj_array)

            PSCTR.update(self.keywords)
            self.PSCTR = OrderedDict(sorted(PSCTR.items(), key=lambda x: x[0]))

            if symbol:
                self._symbol = symbol
            else:
                try:
                    self._symbol = self.keywords["TITEL"].split(" ")[1].strip()
                except IndexError:
                    self._symbol = self.keywords["TITEL"].strip()

            # Compute the POTCAR hashes and check them against the database of known
            # VASP POTCARs
            self.hash = self.get_potcar_hash()
            self.file_hash = self.get_potcar_file_hash()

            if self.identify_potcar(mode='data')[0] == []:
                warnings.warn("POTCAR data with symbol {} does not match any VASP\
                              POTCAR known to pymatgen. We advise verifying the\
                              integrity of your POTCAR files.".format(self.symbol),
                              UnknownPotcarWarning)
            elif self.identify_potcar(mode='file')[0] == []:
                warnings.warn("POTCAR with symbol {} has metadata that does not match\
                              any VASP POTCAR known to pymatgen. The data in this\
                              POTCAR is known to match the following functionals:\
                              {}".format(self.symbol, self.identify_potcar(mode='data')[0]),
                              UnknownPotcarWarning)

        def __str__(self):
            return self.data + "\n"

        @property
        def electron_configuration(self):
            """
            :return: Electronic configuration of the PotcarSingle.
            """
            if not self.nelectrons.is_integer():
                warnings.warn(
                    "POTCAR has non-integer charge, "
                    "electron configuration not well-defined."
                )
                return None
            el = Element.from_Z(self.atomic_no)
            full_config = el.full_electronic_structure
            nelect = self.nelectrons
            config = []
            while nelect > 0:
                e = full_config.pop(-1)
                config.append(e)
                nelect -= e[-1]
            return config

        def write_file(self, filename: str) -> None:
            """
            Writes PotcarSingle to a file.
            :param filename: Filename
            """
            with zopen(filename, "wt") as f:
                f.write(self.__str__())

        @staticmethod
        def from_file(filename: str) -> "PotcarSingle":
            """
            Reads PotcarSingle from file.

            :param filename: Filename.
            :return: PotcarSingle.
            """
            match = re.search(r"(?<=POTCAR\.)(.*)(?=.gz)", str(filename))
            if match:
                symbol = match.group(0)
            else:
                symbol = ""

            try:
                with zopen(filename, "rt") as f:
                    return PotcarSingle(f.read(), symbol=symbol or None)
            except UnicodeDecodeError:
                warnings.warn(
                    "POTCAR contains invalid unicode errors. "
                    "We will attempt to read it by ignoring errors."
                )
                import codecs

                with codecs.open(filename, "r", encoding="utf-8", errors="ignore") as f:
                    return PotcarSingle(f.read(), symbol=symbol or None)

        @staticmethod
        def from_symbol_and_functional(symbol: str, functional: str = None):
            """
            Makes a PotcarSingle from a symbol and functional.

            :param symbol: Symbol, e.g., Li_sv
            :param functional: E.g., PBE
            :return: PotcarSingle
            """
            if functional is None:
                functional = SETTINGS.get("PMG_DEFAULT_FUNCTIONAL", "PBE")
            funcdir = PotcarSingle.functional_dir[functional]
            d = SETTINGS.get("PMG_VASP_PSP_DIR")
            if d is None:
                raise ValueError(
                    "No POTCAR for %s with functional %s found. "
                    "Please set the PMG_VASP_PSP_DIR environment in "
                    ".pmgrc.yaml, or you may need to set "
                    "PMG_DEFAULT_FUNCTIONAL to PBE_52 or PBE_54 if you "
                    "are using newer psps from VASP." % (symbol, functional)
                )
            paths_to_try = [
                os.path.join(d, funcdir, "POTCAR.{}".format(symbol)),
                os.path.join(d, funcdir, symbol, "POTCAR"),
            ]
            for p in paths_to_try:
                p = os.path.expanduser(p)
                p = zpath(p)
                if os.path.exists(p):
                    psingle = PotcarSingle.from_file(p)
                    return psingle
            raise IOError(
                "You do not have the right POTCAR with functional "
                + "{} and label {} in your VASP_PSP_DIR".format(functional, symbol)
            )

        @property
        def element(self):
            """
            Attempt to return the atomic symbol based on the VRHFIN keyword.
            """
            element = self.keywords["VRHFIN"].split(":")[0].strip()
            try:
                return Element(element).symbol
            except ValueError:
                # VASP incorrectly gives the element symbol for Xe as "X"
                # Some potentials, e.g., Zr_sv, gives the symbol as r.
                if element == "X":
                    return "Xe"
                return Element(self.symbol.split("_")[0]).symbol

        @property
        def atomic_no(self) -> int:
            """
            Attempt to return the atomic number based on the VRHFIN keyword.
            """
            return Element(self.element).Z

        @property
        def nelectrons(self):
            """
            :return: Number of electrons
            """
            return self.zval

        @property
        def symbol(self):
            """
            :return: The POTCAR symbol, e.g. W_pv
            """
            return self._symbol

        @property
        def potential_type(self) -> str:
            """
            :return: Type of PSP. E.g., US, PAW, etc.
            """
            if self.lultra:
                return "US"
            elif self.lpaw:
                return "PAW"
            else:
                return "NC"

        @property
        def functional(self):
            """
            :return: Functional associated with PotcarSingle.
            """
            return self.functional_tags.get(self.LEXCH.lower(), {}).get("name")

        @property
        def functional_class(self):
            """
            :return: Functional class associated with PotcarSingle.
            """
            return self.functional_tags.get(self.LEXCH.lower(), {}).get("class")

        def identify_potcar(self, mode: str = 'data'):
            """
            Identify the symbol and compatible functionals associated with this PotcarSingle.

            This method checks the md5 hash of either the POTCAR data (PotcarSingle.hash)
            or the entire POTCAR file (PotcarSingle.file_hash) against a database
            of hashes for POTCARs distributed with VASP 5.4.4.

            Args:
                mode (str): 'data' or 'file'. 'data' mode checks the hash of the POTCAR
                            data itself, while 'file' mode checks the hash of the entire
                            POTCAR file, including metadata.

            Returns:
                symbol (List): List of symbols associated with the PotcarSingle
                potcar_functionals (List): List of potcar functionals associated with
                                           the PotcarSingle
            """
            # Dict to translate the sets in the .json file to the keys used in
            # DictSet
            mapping_dict = {'potUSPP_GGA': {"pymatgen_key": "PW91_US",
                                            "vasp_description": "Ultrasoft pseudo potentials\
                                             for LDA and PW91 (dated 2002-08-20 and 2002-04-08,\
                                             respectively). These files are outdated, not\
                                             supported and only distributed as is."},
                            'potUSPP_LDA': {"pymatgen_key": "LDA_US",
                                            "vasp_description": "Ultrasoft pseudo potentials\
                                             for LDA and PW91 (dated 2002-08-20 and 2002-04-08,\
                                             respectively). These files are outdated, not\
                                             supported and only distributed as is."},
                            'potpaw_GGA': {"pymatgen_key": "PW91",
                                           "vasp_description": "The LDA, PW91 and PBE PAW datasets\
                                            (snapshot: 05-05-2010, 19-09-2006 and 06-05-2010,\
                                            respectively). These files are outdated, not\
                                            supported and only distributed as is."},
                            'potpaw_LDA': {"pymatgen_key": "Perdew-Zunger81",
                                           "vasp_description": "The LDA, PW91 and PBE PAW datasets\
                                            (snapshot: 05-05-2010, 19-09-2006 and 06-05-2010,\
                                            respectively). These files are outdated, not\
                                            supported and only distributed as is."},
                            'potpaw_LDA.52': {"pymatgen_key": "LDA_52",
                                              "vasp_description": "LDA PAW datasets version 52,\
                                               including the early GW variety (snapshot 19-04-2012).\
                                               When read by VASP these files yield identical results\
                                               as the files distributed in 2012 ('unvie' release)."},
                            'potpaw_LDA.54': {"pymatgen_key": "LDA_54",
                                              "vasp_description": "LDA PAW datasets version 54,\
                                               including the GW variety (original release 2015-09-04).\
                                               When read by VASP these files yield identical results as\
                                               the files distributed before."},
                            'potpaw_PBE': {"pymatgen_key": "PBE",
                                           "vasp_description": "The LDA, PW91 and PBE PAW datasets\
                                            (snapshot: 05-05-2010, 19-09-2006 and 06-05-2010,\
                                            respectively). These files are outdated, not\
                                            supported and only distributed as is."},
                            'potpaw_PBE.52': {"pymatgen_key": "PBE_52",
                                              "vasp_description": "PBE PAW datasets version 52,\
                                               including early GW variety (snapshot 19-04-2012).\
                                               When read by VASP these files yield identical\
                                               results as the files distributed in 2012."},
                            'potpaw_PBE.54': {"pymatgen_key": "PBE_54",
                                              "vasp_description": "PBE PAW datasets version 54,\
                                               including the GW variety (original release 2015-09-04).\
                                               When read by VASP these files yield identical results as\
                                               the files distributed before."},
                            'unvie_potpaw.52': {"pymatgen_key": "unvie_LDA_52",
                                                "vasp_description": "files released previously\
                                                 for vasp.5.2 (2012-04) and vasp.5.4 (2015-09-04)\
                                                 by univie."},
                            'unvie_potpaw.54': {"pymatgen_key": "unvie_LDA_54",
                                                "vasp_description": "files released previously\
                                                 for vasp.5.2 (2012-04) and vasp.5.4 (2015-09-04)\
                                                 by univie."},
                            'unvie_potpaw_PBE.52': {"pymatgen_key": "unvie_PBE_52",
                                                    "vasp_description": "files released previously\
                                                    for vasp.5.2 (2012-04) and vasp.5.4 (2015-09-04)\
                                                    by univie."},
                            'unvie_potpaw_PBE.54': {"pymatgen_key": "unvie_PBE_52",
                                                    "vasp_description": "files released previously\
                                                    for vasp.5.2 (2012-04) and vasp.5.4 (2015-09-04)\
                                                    by univie."}
                            }

            cwd = os.path.abspath(os.path.dirname(__file__))

            if mode == 'data':
                hash_db = loadfn(os.path.join(cwd, "vasp_potcar_pymatgen_hashes.json"))
                potcar_hash = self.hash
            elif mode == 'file':
                hash_db = loadfn(os.path.join(cwd, "vasp_potcar_file_hashes.json"))
                potcar_hash = self.file_hash
            else:
                raise ValueError("Bad 'mode' argument. Specify 'data' or 'file'.")

            identity = hash_db.get(potcar_hash)

            if identity:
                # convert the potcar_functionals from the .json dict into the functional
                # keys that pymatgen uses
                potcar_functionals = []
                for i in identity["potcar_functionals"]:
                    potcar_functionals.append(mapping_dict[i]["pymatgen_key"])
                potcar_functionals = list(set(potcar_functionals))

                return potcar_functionals, identity["potcar_symbols"]
            else:
                return [], []

        def get_potcar_file_hash(self):
            """
            Computes a hash of the entire PotcarSingle.

            This hash corresponds to the md5 hash of the POTCAR file itself.

            :return: Hash value.
            """
            return md5(self.data.encode("utf-8")).hexdigest()

        def get_potcar_hash(self):
            """
            Computes a md5 hash of the data defining the PotcarSingle.

            :return: Hash value.
            """
            hash_str = ""
            for k, v in self.PSCTR.items():
                hash_str += "{}".format(k)
                if isinstance(v, int):
                    hash_str += "{}".format(v)
                elif isinstance(v, float):
                    hash_str += "{:.3f}".format(v)
                elif isinstance(v, bool):
                    hash_str += "{}".format(bool)
                elif isinstance(v, (tuple, list)):
                    for item in v:
                        if isinstance(item, float):
                            hash_str += "{:.3f}".format(item)
                        elif isinstance(item, (Orbital, OrbitalDescription)):
                            for item_v in item:
                                if isinstance(item_v, (int, str)):
                                    hash_str += "{}".format(item_v)
                                elif isinstance(item_v, float):
                                    hash_str += "{:.3f}".format(item_v)
                                else:
                                    hash_str += "{}".format(item_v) if item_v else ""
                else:
                    hash_str += v.replace(" ", "")

            self.hash_str = hash_str
            return md5(hash_str.lower().encode("utf-8")).hexdigest()

        def __getattr__(self, a):
            """
            Delegates attributes to keywords. For example, you can use
            potcarsingle.enmax to get the ENMAX of the POTCAR.

            For float type properties, they are converted to the correct float. By
            default, all energies in eV and all length scales are in Angstroms.
            """

            try:
                return self.keywords[a.upper()]
            except Exception:
                raise AttributeError(a)

    class Potcar(list, MSONable):
        """
        Object for reading and writing POTCAR files for calculations. Consists of a
        list of PotcarSingle.
        """

        FUNCTIONAL_CHOICES = list(PotcarSingle.functional_dir.keys())

        def __init__(self, symbols=None, functional=None, sym_potcar_map=None):
            """
            Args:
                symbols ([str]): Element symbols for POTCAR. This should correspond
                    to the symbols used by VASP. E.g., "Mg", "Fe_pv", etc.
                functional (str): Functional used. To know what functional options
                    there are, use Potcar.FUNCTIONAL_CHOICES. Note that VASP has
                    different versions of the same functional. By default, the old
                    PBE functional is used. If you want the newer ones, use PBE_52 or
                    PBE_54. Note that if you intend to compare your results with the
                    Materials Project, you should use the default setting. You can also
                    override the default by setting PMG_DEFAULT_FUNCTIONAL in your
                    .pmgrc.yaml.
                sym_potcar_map (dict): Allows a user to specify a specific element
                    symbol to raw POTCAR mapping.
            """
            if functional is None:
                functional = SETTINGS.get("PMG_DEFAULT_FUNCTIONAL", "PBE")
            super().__init__()
            self.functional = functional
            if symbols is not None:
                self.set_symbols(symbols, functional, sym_potcar_map)

        def as_dict(self):
            """
            :return: MSONable dict representation
            """
            return {
                "functional": self.functional,
                "symbols": self.symbols,
                "@module": self.__class__.__module__,
                "@class": self.__class__.__name__,
            }

        @classmethod
        def from_dict(cls, d):
            """
            :param d: Dict representation
            :return: Potcar
            """
            return Potcar(symbols=d["symbols"], functional=d["functional"])

        @staticmethod
        def from_file(filename: str):
            """
            Reads Potcar from file.

            :param filename: Filename
            :return: Potcar
            """
            try:
                with zopen(filename, "rt") as f:
                    fdata = f.read()
            except UnicodeDecodeError:
                warnings.warn(
                    "POTCAR contains invalid unicode errors. "
                    "We will attempt to read it by ignoring errors."
                )
                import codecs

                with codecs.open(filename, "r", encoding="utf-8", errors="ignore") as f:
                    fdata = f.read()

            potcar = Potcar()
            potcar_strings = re.compile(r"\n?(\s*.*?End of Dataset)", re.S).findall(fdata)
            functionals = []
            for p in potcar_strings:
                single = PotcarSingle(p)
                potcar.append(single)
                functionals.append(single.functional)
            if len(set(functionals)) != 1:
                raise ValueError("File contains incompatible functionals!")
            else:
                potcar.functional = functionals[0]
            return potcar

        def __str__(self):
            return "\n".join([str(potcar).strip("\n") for potcar in self]) + "\n"

        def write_file(self, filename):
            """
            Write Potcar to a file.

            Args:
                filename (str): filename to write to.
            """
            with zopen(filename, "wt") as f:
                f.write(self.__str__())

        @property
        def symbols(self):
            """
            Get the atomic symbols of all the atoms in the POTCAR file.
            """
            return [p.symbol for p in self]

        @symbols.setter
        def symbols(self, symbols):
            self.set_symbols(symbols, functional=self.functional)

        @property
        def spec(self):
            """
            Get the atomic symbols and hash of all the atoms in the POTCAR file.
            """
            return [{"symbol": p.symbol, "hash": p.get_potcar_hash()} for p in self]

        def set_symbols(self, symbols, functional=None, sym_potcar_map=None):
            """
            Initialize the POTCAR from a set of symbols. Currently, the POTCARs can
            be fetched from a location specified in .pmgrc.yaml. Use pmg config
            to add this setting.

            Args:
                symbols ([str]): A list of element symbols
                functional (str): The functional to use. If None, the setting
                    PMG_DEFAULT_FUNCTIONAL in .pmgrc.yaml is used, or if this is
                    not set, it will default to PBE.
                sym_potcar_map (dict): A map of symbol:raw POTCAR string. If
                    sym_potcar_map is specified, POTCARs will be generated from
                    the given map data rather than the config file location.
            """
            del self[:]
            if sym_potcar_map:
                for el in symbols:
                    self.append(PotcarSingle(sym_potcar_map[el]))
            else:
                for el in symbols:
                    p = PotcarSingle.from_symbol_and_functional(el, functional)
                    self.append(p)

    class VaspInput(dict, MSONable):
        """
        Class to contain a set of vasp input objects corresponding to a run.
        """

        def __init__(self, incar, kpoints, poscar, potcar, optional_files=None, **kwargs):
            """
            Args:
                incar: Incar object.
                kpoints: Kpoints object.
                poscar: Poscar object.
                potcar: Potcar object.
                optional_files: Other input files supplied as a dict of {
                    filename: object}. The object should follow standard pymatgen
                    conventions in implementing a as_dict() and from_dict method.
            """
            super().__init__(**kwargs)
            self.update(
                {"INCAR": incar, "KPOINTS": kpoints, "POSCAR": poscar, "POTCAR": potcar}
            )
            if optional_files is not None:
                self.update(optional_files)

        def __str__(self):
            output = []
            for k, v in self.items():
                output.append(k)
                output.append(str(v))
                output.append("")
            return "\n".join(output)

        def as_dict(self):
            """
            :return: MSONable dict.
            """
            d = {k: v.as_dict() for k, v in self.items()}
            d["@module"] = self.__class__.__module__
            d["@class"] = self.__class__.__name__
            return d

        @classmethod
        def from_dict(cls, d):
            """
            :param d: Dict representation.
            :return: VaspInput
            """
            dec = MontyDecoder()
            sub_d = {"optional_files": {}}
            for k, v in d.items():
                if k in ["INCAR", "POSCAR", "POTCAR", "KPOINTS"]:
                    sub_d[k.lower()] = dec.process_decoded(v)
                elif k not in ["@module", "@class"]:
                    sub_d["optional_files"][k] = dec.process_decoded(v)
            return cls(**sub_d)

        def write_input(self, output_dir=".", make_dir_if_not_present=True):
            """
            Write VASP input to a directory.

            Args:
                output_dir (str): Directory to write to. Defaults to current
                    directory (".").
                make_dir_if_not_present (bool): Create the directory if not
                    present. Defaults to True.
            """
            if make_dir_if_not_present and not os.path.exists(output_dir):
                os.makedirs(output_dir)
            for k, v in self.items():
                if v is not None:
                    with zopen(os.path.join(output_dir, k), "wt") as f:
                        f.write(v.__str__())

        @staticmethod
        def from_directory(input_dir, optional_files=None):
            """
            Read in a set of VASP input from a directory. Note that only the
            standard INCAR, POSCAR, POTCAR and KPOINTS files are read unless
            optional_filenames is specified.

            Args:
                input_dir (str): Directory to read VASP input from.
                optional_files (dict): Optional files to read in as well as a
                    dict of {filename: Object type}. Object type must have a
                    static method from_file.
            """
            sub_d = {}
            for fname, ftype in [
                ("INCAR", Incar),
                ("KPOINTS", Kpoints),
                ("POSCAR", Poscar),
                ("POTCAR", Potcar),
            ]:
                try:
                    fullzpath = zpath(os.path.join(input_dir, fname))
                    sub_d[fname.lower()] = ftype.from_file(fullzpath)
                except FileNotFoundError:  # handle the case where there is no KPOINTS file
                    sub_d[fname.lower()] = None
                    pass

            sub_d["optional_files"] = {}
            if optional_files is not None:
                for fname, ftype in optional_files.items():
                    sub_d["optional_files"][fname] = ftype.from_file(
                        os.path.join(input_dir, fname)
                    )
            return VaspInput(**sub_d)

        def run_vasp(
            self,
            run_dir: PathLike = ".",
            vasp_cmd: list = None,
            output_file: PathLike = "vasp.out",
            err_file: PathLike = "vasp.err",
        ):
            """
            Write input files and run VASP.

            :param run_dir: Where to write input files and do the run.
            :param vasp_cmd: Args to be supplied to run VASP. Otherwise, the
                PMG_VASP_EXE in .pmgrc.yaml is used.
            :param output_file: File to write output.
            :param err_file: File to write err.
            """
            self.write_input(output_dir=run_dir)
            vasp_cmd = vasp_cmd or SETTINGS.get("PMG_VASP_EXE")
            vasp_cmd = [os.path.expanduser(os.path.expandvars(t)) for t in vasp_cmd]
            if not vasp_cmd:
                raise RuntimeError(
                    "You need to supply vasp_cmd or set the PMG_VASP_EXE in .pmgrc.yaml to run VASP."
                )
            with cd(run_dir):
                with open(output_file, "w") as f_std, open(
                    err_file, "w", buffering=1
                ) as f_err:
                    subprocess.check_call(vasp_cmd, stdout=f_std, stderr=f_err)