/* -*- c++ -*- ----------------------------------------------------------
   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
   https://www.lammps.org/, Sandia National Laboratories
   Steve Plimpton, sjplimp@sandia.gov

   Copyright (2003) Sandia Corporation.  Under the terms of Contract
   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
   certain rights in this software.  This software is distributed under
   the GNU General Public License.

   See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */

#ifdef PAIR_CLASS
// clang-format off
PairStyle(lj/cut/tip4p/cut,PairLJCutTIP4PCut);
// clang-format on
#else

#ifndef LMP_PAIR_LJ_CUT_TIP4P_CUT_H
#define LMP_PAIR_LJ_CUT_TIP4P_CUT_H

#include "pair.h"

namespace LAMMPS_NS {

class PairLJCutTIP4PCut : public Pair {
 public:
  PairLJCutTIP4PCut(class LAMMPS *);
  virtual ~PairLJCutTIP4PCut();
  virtual void compute(int, int);
  void settings(int, char **);
  void coeff(int, char **);
  void init_style();
  double init_one(int, int);
  virtual void write_restart_settings(FILE *);
  virtual void read_restart_settings(FILE *);
  void write_restart(FILE *);
  void read_restart(FILE *);
  void write_data(FILE *);
  void write_data_all(FILE *);
  void *extract(const char *, int &);
  double memory_usage();

 protected:
  double cut_lj_global, cut_coul_global;
  double cut_coul, cut_coulsq;
  double cut_coulsqplus;    // extended value for cut_coulsq
  double **cut_lj, **cut_ljsq;
  double **epsilon, **sigma;
  double **lj1, **lj2, **lj3, **lj4, **offset;

  int typeH, typeO;    // atom types of TIP4P water H and O atoms
  int typeA, typeB;    // angle and bond types of TIP4P water
  double alpha;        // geometric constraint parameter for TIP4P
  double qdist;

  int nmax;            // info on off-oxygen charge sites
  int **hneigh;        // 0,1 = indices of 2 H associated with O
                       // 2 = 0 if site loc not yet computed, 1 if yes
  double **newsite;    // locations of charge sites

  void allocate();
  void compute_newsite(double *, double *, double *, double *);
};
}    // namespace LAMMPS_NS

#endif
#endif

/* ERROR/WARNING messages:

E: TIP4P hydrogen is missing

The TIP4P pairwise computation failed to find the correct H atom
within a water molecule.

E: TIP4P hydrogen has incorrect atom type

The TIP4P pairwise computation found an H atom whose type does not
agree with the specified H type.

E: Illegal ... command

Self-explanatory.  Check the input script syntax and compare to the
documentation for the command.  You can use -echo screen as a
command-line option when running LAMMPS to see the offending line.

E: Incorrect args for pair coefficients

Self-explanatory.  Check the input script or data file.

E: Pair style lj/cut/tip4p/cut requires atom IDs

This is a requirement to use this potential.

E: Pair style lj/cut/tip4p/cut requires newton pair on

See the newton command.  This is a restriction to use this
potential.

E: Pair style lj/cut/tip4p/cut requires atom attribute q

The atom style defined does not have this attribute.

E: Must use a bond style with TIP4P potential

TIP4P potentials assume bond lengths in water are constrained
by a fix shake command.

E: Must use an angle style with TIP4P potential

TIP4P potentials assume angles in water are constrained by a fix shake
command.

E: Water H epsilon must be 0.0 for pair style lj/cut/tip4p/cut

This is because LAMMPS does not compute the Lennard-Jones interactions
with these particles for efficiency reasons.

*/
