source files for pair coul/slater

/* ----------------------------------------------------------------------

   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator

   http://lammps.sandia.gov, 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.

------------------------------------------------------------------------- */

/* ----------------------------------------------------------------------

 *     Contributing author:  Evangelos Voyiatzis (Royal DSM)

 * ------------------------------------------------------------------------- */

#include <cmath>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include "pair_coul_slater_cut.h"

#include "atom.h"

#include "comm.h"

#include "force.h"

#include "neighbor.h"

#include "neigh_list.h"

#include "memory.h"

#include "error.h"

using namespace LAMMPS_NS;

/* ---------------------------------------------------------------------- */

PairCoulSlaterCut::PairCoulSlaterCut(LAMMPS *lmp) : PairCoulCut(lmp) {}

/* ---------------------------------------------------------------------- */

void PairCoulSlaterCut::compute(int eflag, int vflag)

{

  int i,j,ii,jj,inum,jnum,itype,jtype;

  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,ecoul,fpair;

  double rsq,r2inv,r,rinv,forcecoul,factor_coul,bracket_term;

  int *ilist,*jlist,*numneigh,**firstneigh;

  ecoul = 0.0;

  if (eflag || vflag) ev_setup(eflag,vflag);

  else evflag = vflag_fdotr = 0;

  double **x = atom->x;

  double **f = atom->f;

  double *q = atom->q;

  int *type = atom->type;

  int nlocal = atom->nlocal;

  double *special_coul = force->special_coul;

  int newton_pair = force->newton_pair;

  double qqrd2e = force->qqrd2e;

  inum = list->inum;

  ilist = list->ilist;

  numneigh = list->numneigh;

  firstneigh = list->firstneigh;

  // loop over neighbors of my atoms

  for (ii = 0; ii < inum; ii++) {

    i = ilist[ii];

    qtmp = q[i];

    xtmp = x[i][0];

    ytmp = x[i][1];

    ztmp = x[i][2];

    itype = type[i];

    jlist = firstneigh[i];

    jnum = numneigh[i];

    for (jj = 0; jj < jnum; jj++) {

      j = jlist[jj];

      factor_coul = special_coul[sbmask(j)];

      j &= NEIGHMASK;

      delx = xtmp - x[j][0];

      dely = ytmp - x[j][1];

      delz = ztmp - x[j][2];

      rsq = delx*delx + dely*dely + delz*delz;

      jtype = type[j];

      if (rsq < cutsq[itype][jtype]) {

        r2inv = 1.0/rsq;

        r = sqrt(rsq);

        rinv = 1.0/r;

        bracket_term = 1 - exp(-2*r/lamda)*(1 + (2*r/lamda*(1+r/lamda)));

        forcecoul = qqrd2e * scale[itype][jtype] *

          qtmp*q[j] * bracket_term * rinv;

        fpair = factor_coul*forcecoul * r2inv;

        f[i][0] += delx*fpair;

        f[i][1] += dely*fpair;

        f[i][2] += delz*fpair;

        if (newton_pair || j < nlocal) {

          f[j][0] -= delx*fpair;

          f[j][1] -= dely*fpair;

          f[j][2] -= delz*fpair;

        }

        if (eflag) ecoul = factor_coul * qqrd2e *

            scale[itype][jtype] * qtmp*q[j] * rinv * 

            (1 - (1 + r/lamda)*exp(-2*r/lamda));

        if (evflag) ev_tally(i,j,nlocal,newton_pair,

                             0.0,ecoul,fpair,delx,dely,delz);

      }

    }

  }

  if (vflag_fdotr) virial_fdotr_compute();

}

/* ----------------------------------------------------------------------

   global settings

------------------------------------------------------------------------- */

void PairCoulSlaterCut::settings(int narg, char **arg)

{

  if (narg != 2) error->all(FLERR,"Illegal pair_style command");

  lamda = force->numeric(FLERR,arg[0]);

  cut_global = force->numeric(FLERR,arg[1]);

  // reset cutoffs that have been explicitly set

  if (allocated) {

    int i,j;

    for (i = 1; i <= atom->ntypes; i++)

      for (j = i; j <= atom->ntypes; j++)

        if (setflag[i][j]) cut[i][j] = cut_global;

  }

}

/* ----------------------------------------------------------------------

  proc 0 writes to restart file

------------------------------------------------------------------------- */

void PairCoulSlaterCut::write_restart_settings(FILE *fp)

{

  fwrite(&cut_global,sizeof(double),1,fp);

  fwrite(&lamda,sizeof(double),1,fp);

  fwrite(&offset_flag,sizeof(int),1,fp);

  fwrite(&mix_flag,sizeof(int),1,fp);

}

/* ----------------------------------------------------------------------

  proc 0 reads from restart file, bcasts

------------------------------------------------------------------------- */

void PairCoulSlaterCut::read_restart_settings(FILE *fp)

{

  if (comm->me == 0) {

    fread(&cut_global,sizeof(double),1,fp);

    fread(&lamda,sizeof(double),1,fp);

    fread(&offset_flag,sizeof(int),1,fp);

    fread(&mix_flag,sizeof(int),1,fp);

  }

  MPI_Bcast(&cut_global,1,MPI_DOUBLE,0,world);

  MPI_Bcast(&lamda,1,MPI_DOUBLE,0,world);

  MPI_Bcast(&offset_flag,1,MPI_INT,0,world);

  MPI_Bcast(&mix_flag,1,MPI_INT,0,world);

}

/* ---------------------------------------------------------------------- */

double PairCoulSlaterCut::single(int i, int j, int /*itype*/, int /*jtype*/,

                           double rsq, double factor_coul, double /*factor_lj*/,

                           double &fforce)

{

  double r2inv,r,rinv,forcecoul,phicoul,bracket_term;

  r2inv = 1.0/rsq;

  r = sqrt(rsq);

  rinv = 1.0/r;

  bracket_term = 1 - exp(-2*r/lamda)*(1 + (2*r/lamda*(1+r/lamda)));

  forcecoul = force->qqrd2e * atom->q[i]*atom->q[j] *

     bracket_term * rinv;

  fforce = factor_coul*forcecoul * r2inv;

  phicoul = force->qqrd2e * atom->q[i]*atom->q[j] * rinv * (1 - (1 + r/lamda)*exp(-2*r/lamda));

  return factor_coul*phicoul;

}

/* -*- c++ -*- ----------------------------------------------------------

   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator

   http://lammps.sandia.gov, 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

PairStyle(coul/slater/cut,PairCoulSlaterCut)

#else

#ifndef LMP_PAIR_COUL_SLATER_CUT_H

#define LMP_PAIR_COUL_SLATER_CUT_H

#include "pair_coul_cut.h"

namespace LAMMPS_NS {

class PairCoulSlaterCut : public PairCoulCut {

 public:

  PairCoulSlaterCut(class LAMMPS *);

  virtual void compute(int, int);

  void settings(int, char **);

  void write_restart_settings(FILE *);

  void read_restart_settings(FILE *);

  double single(int, int, int, int, double, double, double, double &);

 protected:

  double lamda;

};

}

#endif

#endif

/* ERROR/WARNING messages:

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.

*/

/* ----------------------------------------------------------------------

   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator

   http://lammps.sandia.gov, 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.

------------------------------------------------------------------------- */

/* ----------------------------------------------------------------------

 *     Contributing author:  Evangelos Voyiatzis (Royal DSM)

 * ------------------------------------------------------------------------- */

#include <cmath>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include "pair_coul_slater_long.h"

#include "atom.h"

#include "comm.h"

#include "force.h"

#include "kspace.h"

#include "neighbor.h"

#include "neigh_list.h"

#include "update.h"

#include "integrate.h"

#include "respa.h"

#include "memory.h"

#include "error.h"

using namespace LAMMPS_NS;

#define EWALD_F   1.12837917

#define EWALD_P   0.3275911

#define A1        0.254829592

#define A2       -0.284496736

#define A3        1.421413741

#define A4       -1.453152027

#define A5        1.061405429

/* ---------------------------------------------------------------------- */

PairCoulSlaterLong::PairCoulSlaterLong(LAMMPS *lmp) : Pair(lmp)

{

  ewaldflag = pppmflag = 1;

  //ftable = NULL;

  qdist = 0.0;

}

/* ---------------------------------------------------------------------- */

PairCoulSlaterLong::~PairCoulSlaterLong()

{

  if (!copymode) {

    if (allocated) {

      memory->destroy(setflag);

      memory->destroy(cutsq);

      memory->destroy(scale);

    }

    //if (ftable) free_tables();

  }

}

/* ---------------------------------------------------------------------- */

void PairCoulSlaterLong::compute(int eflag, int vflag)

{

  int i,j,ii,jj,inum,jnum,itype,jtype;

  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,ecoul,fpair;

//  double fraction,table;

  double r,r2inv,forcecoul,factor_coul;

  double grij,expm2,prefactor,t,erfc;

  int *ilist,*jlist,*numneigh,**firstneigh;

  double rsq;

  double slater_term;

//  int itable;

  ecoul = 0.0;

  if (eflag || vflag) ev_setup(eflag,vflag);

  else evflag = vflag_fdotr = 0;

  double **x = atom->x;

  double **f = atom->f;

  double *q = atom->q;

  int *type = atom->type;

  int nlocal = atom->nlocal;

  double *special_coul = force->special_coul;

  int newton_pair = force->newton_pair;

  double qqrd2e = force->qqrd2e;

  inum = list->inum;

  ilist = list->ilist;

  numneigh = list->numneigh;

  firstneigh = list->firstneigh;

  // loop over neighbors of my atoms

  for (ii = 0; ii < inum; ii++) {

    i = ilist[ii];

    qtmp = q[i];

    xtmp = x[i][0];

    ytmp = x[i][1];

    ztmp = x[i][2];

    itype = type[i];

    jlist = firstneigh[i];

    jnum = numneigh[i];

    for (jj = 0; jj < jnum; jj++) {

      j = jlist[jj];

      factor_coul = special_coul[sbmask(j)];

      j &= NEIGHMASK;

      delx = xtmp - x[j][0];

      dely = ytmp - x[j][1];

      delz = ztmp - x[j][2];

      rsq = delx*delx + dely*dely + delz*delz;

      jtype = type[j];

      if (rsq < cut_coulsq) {

        r2inv = 1.0/rsq;

//        if (!ncoultablebits || rsq <= tabinnersq) {

          r = sqrt(rsq);

          grij = g_ewald * r;

          expm2 = exp(-grij*grij);

          t = 1.0 / (1.0 + EWALD_P*grij);

          erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;

          slater_term = exp(-2*r/lamda)*(1 + (2*r/lamda*(1+r/lamda)));

          prefactor = qqrd2e * scale[itype][jtype] * qtmp*q[j]/r;

          forcecoul = prefactor * (erfc + EWALD_F*grij*expm2 - slater_term);

          if (factor_coul < 1.0) forcecoul -= (1.0-factor_coul)*prefactor;

/*

        } else {

          union_int_float_t rsq_lookup;

          rsq_lookup.f = rsq;

          itable = rsq_lookup.i & ncoulmask;

          itable >>= ncoulshiftbits;

          fraction = (rsq_lookup.f - rtable[itable]) * drtable[itable];

          table = ftable[itable] + fraction*dftable[itable];

          forcecoul = scale[itype][jtype] * qtmp*q[j] * table;

          if (factor_coul < 1.0) {

            table = ctable[itable] + fraction*dctable[itable];

            prefactor = scale[itype][jtype] * qtmp*q[j] * table;

            forcecoul -= (1.0-factor_coul)*prefactor;

          }

        }

*/

        fpair = forcecoul * r2inv;

        f[i][0] += delx*fpair;

        f[i][1] += dely*fpair;

        f[i][2] += delz*fpair;

        if (newton_pair || j < nlocal) {

          f[j][0] -= delx*fpair;

          f[j][1] -= dely*fpair;

          f[j][2] -= delz*fpair;

        }

        if (eflag) {

//          if (!ncoultablebits || rsq <= tabinnersq)

            ecoul = prefactor*(erfc - (1 + r/lamda)*exp(-2*r/lamda));

/*

          else {

            table = etable[itable] + fraction*detable[itable];

            ecoul = scale[itype][jtype] * qtmp*q[j] * table;

          }

*/

          if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;

        }

        if (evflag) ev_tally(i,j,nlocal,newton_pair,

                             0.0,ecoul,fpair,delx,dely,delz);

      }

    }

  }

  if (vflag_fdotr) virial_fdotr_compute();

}

/* ----------------------------------------------------------------------

   allocate all arrays

------------------------------------------------------------------------- */

void PairCoulSlaterLong::allocate()

{

  allocated = 1;

  int n = atom->ntypes;

  memory->create(setflag,n+1,n+1,"pair:setflag");

  for (int i = 1; i <= n; i++)

    for (int j = i; j <= n; j++)

      setflag[i][j] = 0;

  memory->create(cutsq,n+1,n+1,"pair:cutsq");

  memory->create(scale,n+1,n+1,"pair:scale");

}

/* ----------------------------------------------------------------------

   global settings

------------------------------------------------------------------------- */

void PairCoulSlaterLong::settings(int narg, char **arg)

{

  if (narg != 2) error->all(FLERR,"Illegal pair_style command");

  lamda = force->numeric(FLERR,arg[0]);

  cut_coul = force->numeric(FLERR,arg[1]);

}

/* ----------------------------------------------------------------------

   set coeffs for one or more type pairs

------------------------------------------------------------------------- */

void PairCoulSlaterLong::coeff(int narg, char **arg)

{

  if (narg != 2) error->all(FLERR,"Incorrect args for pair coefficients");

  if (!allocated) allocate();

  int ilo,ihi,jlo,jhi;

  force->bounds(FLERR,arg[0],atom->ntypes,ilo,ihi);

  force->bounds(FLERR,arg[1],atom->ntypes,jlo,jhi);

  int count = 0;

  for (int i = ilo; i <= ihi; i++) {

    for (int j = MAX(jlo,i); j <= jhi; j++) {

      scale[i][j] = 1.0;

      setflag[i][j] = 1;

      count++;

    }

  }

  if (count == 0) error->all(FLERR,"Incorrect args for pair coefficients");

}

/* ----------------------------------------------------------------------

   init specific to this pair style

------------------------------------------------------------------------- */

void PairCoulSlaterLong::init_style()

{

  if (!atom->q_flag)

    error->all(FLERR,"Pair style coul/slater/long requires atom attribute q");

  neighbor->request(this,instance_me);

  cut_coulsq = cut_coul * cut_coul;

  // insure use of KSpace long-range solver, set g_ewald

 if (force->kspace == NULL)

    error->all(FLERR,"Pair style requires a KSpace style");

  g_ewald = force->kspace->g_ewald;

  // setup force tables

  // if (ncoultablebits) init_tables(cut_coul,NULL);

}

/* ----------------------------------------------------------------------

   init for one type pair i,j and corresponding j,i

------------------------------------------------------------------------- */

double PairCoulSlaterLong::init_one(int i, int j)

{

  scale[j][i] = scale[i][j];

  return cut_coul+2.0*qdist;

}

/* ----------------------------------------------------------------------

  proc 0 writes to restart file

------------------------------------------------------------------------- */

void PairCoulSlaterLong::write_restart(FILE *fp)

{

  write_restart_settings(fp);

  for (int i = 1; i <= atom->ntypes; i++)

    for (int j = i; j <= atom->ntypes; j++) {

      fwrite(&setflag[i][j],sizeof(int),1,fp);

      if (setflag[i][j])

        fwrite(&scale[i][j],sizeof(double),1,fp);

    }

}

/* ----------------------------------------------------------------------

  proc 0 reads from restart file, bcasts

------------------------------------------------------------------------- */

void PairCoulSlaterLong::read_restart(FILE *fp)

{

  read_restart_settings(fp);

  allocate();

  int i,j;

  int me = comm->me;

  for (i = 1; i <= atom->ntypes; i++)

    for (j = i; j <= atom->ntypes; j++) {

      if (me == 0) fread(&setflag[i][j],sizeof(int),1,fp);

      MPI_Bcast(&setflag[i][j],1,MPI_INT,0,world);

      if (setflag[i][j]) {

        if (me == 0) fread(&scale[i][j],sizeof(double),1,fp);

        MPI_Bcast(&scale[i][j],1,MPI_DOUBLE,0,world);

      }

    }

}

/* ----------------------------------------------------------------------

  proc 0 writes to restart file

------------------------------------------------------------------------- */

void PairCoulSlaterLong::write_restart_settings(FILE *fp)

{

  fwrite(&cut_coul,sizeof(double),1,fp);

  fwrite(&lamda,sizeof(double),1,fp);

  fwrite(&offset_flag,sizeof(int),1,fp);

  fwrite(&mix_flag,sizeof(int),1,fp);

  //fwrite(&ncoultablebits,sizeof(int),1,fp);

  //fwrite(&tabinner,sizeof(double),1,fp);

}

/* ----------------------------------------------------------------------

  proc 0 reads from restart file, bcasts

------------------------------------------------------------------------- */

void PairCoulSlaterLong::read_restart_settings(FILE *fp)

{

  if (comm->me == 0) {

    fread(&cut_coul,sizeof(double),1,fp);

    fread(&lamda,sizeof(double),1,fp);

    fread(&offset_flag,sizeof(int),1,fp);

    fread(&mix_flag,sizeof(int),1,fp);

    //fread(&ncoultablebits,sizeof(int),1,fp);

    //fread(&tabinner,sizeof(double),1,fp);

  }

  MPI_Bcast(&cut_coul,1,MPI_DOUBLE,0,world);

  MPI_Bcast(&lamda,1,MPI_DOUBLE,0,world);

  MPI_Bcast(&offset_flag,1,MPI_INT,0,world);

  MPI_Bcast(&mix_flag,1,MPI_INT,0,world);

  //MPI_Bcast(&ncoultablebits,1,MPI_INT,0,world);

  //MPI_Bcast(&tabinner,1,MPI_DOUBLE,0,world);

}

/* ---------------------------------------------------------------------- */

double PairCoulSlaterLong::single(int i, int j, int /*itype*/, int /*jtype*/,

                            double rsq,

                            double factor_coul, double /*factor_lj*/,

                            double &fforce)

{

  double r2inv,r,grij,expm2,t,erfc,prefactor;

  double slater_term;

//  double fraction,table;

  double forcecoul,phicoul;

//  int itable;

  r2inv = 1.0/rsq;

//  if (!ncoultablebits || rsq <= tabinnersq) {

    r = sqrt(rsq);

    grij = g_ewald * r;

    expm2 = exp(-grij*grij);

    t = 1.0 / (1.0 + EWALD_P*grij);

    erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;

    slater_term = exp(-2*r/lamda)*(1 + (2*r/lamda*(1+r/lamda)));

    prefactor = force->qqrd2e * atom->q[i]*atom->q[j]/r;

    forcecoul = prefactor * (erfc + EWALD_F*grij*expm2 - slater_term);

    if (factor_coul < 1.0) forcecoul -= (1.0-factor_coul)*prefactor;

/*

  } else {

    union_int_float_t rsq_lookup;

    rsq_lookup.f = rsq;

    itable = rsq_lookup.i & ncoulmask;

    itable >>= ncoulshiftbits;

    fraction = (rsq_lookup.f - rtable[itable]) * drtable[itable];

    table = ftable[itable] + fraction*dftable[itable];

    forcecoul = atom->q[i]*atom->q[j] * table;

    if (factor_coul < 1.0) {

      table = ctable[itable] + fraction*dctable[itable];

      prefactor = atom->q[i]*atom->q[j] * table;

      forcecoul -= (1.0-factor_coul)*prefactor;

    }

  }

*/

  fforce = forcecoul * r2inv;

//  if (!ncoultablebits || rsq <= tabinnersq)

    phicoul = prefactor*(erfc - (1 + r/lamda)*exp(-2*r/lamda));

/*

  else {

    table = etable[itable] + fraction*detable[itable];

    phicoul = atom->q[i]*atom->q[j] * table;

  }

*/

  if (factor_coul < 1.0) phicoul -= (1.0-factor_coul)*prefactor;

  return phicoul;

}

/* ---------------------------------------------------------------------- */

void *PairCoulSlaterLong::extract(const char *str, int &dim)

{

  if (strcmp(str,"cut_coul") == 0) {

    dim = 0;

    return (void *) &cut_coul;

  }