Commit bc528eda authored by sjplimp's avatar sjplimp
Browse files 

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@931 f3b2605a-c512-4ea7-a41b-209d697bcdaa
parent 201466f4

src/KSPACE/Install.csh

+4 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ if ($1 == 1) then 
  cp pppm.cpp ..

  cp pppm_tip4p.cpp ..

  cp pair_buck_coul_long.cpp ..

  cp pair_coul_long.cpp ..

  cp pair_lj_cut_coul_long.cpp ..

  cp pair_lj_cut_coul_long_tip4p.cpp ..

  cp pair_lj_charmm_coul_long.cpp ..
@@ -20,6 +21,7 @@ if ($1 == 1) then 
  cp pppm.h ..

  cp pppm_tip4p.h ..

  cp pair_buck_coul_long.h ..

  cp pair_coul_long.h ..

  cp pair_lj_cut_coul_long.h ..

  cp pair_lj_cut_coul_long_tip4p.h ..

  cp pair_lj_charmm_coul_long.h ..
@@ -37,6 +39,7 @@ else if ($1 == 0) then 
  rm ../pppm.cpp

  rm ../pppm_tip4p.cpp

  rm ../pair_buck_coul_long.cpp

  rm ../pair_coul_long.cpp

  rm ../pair_lj_cut_coul_long.cpp

  rm ../pair_lj_cut_coul_long_tip4p.cpp

  rm ../pair_lj_charmm_coul_long.cpp
@@ -49,6 +52,7 @@ else if ($1 == 0) then 
  rm ../pppm.h

  rm ../pppm_tip4p.h

  rm ../pair_buck_coul_long.h

  rm ../pair_coul_long.h

  rm ../pair_lj_cut_coul_long.h

  rm ../pair_lj_cut_coul_long_tip4p.h

  rm ../pair_lj_charmm_coul_long.h

src/KSPACE/pair_buck_coul_long.cpp

+18 −12
Original line number Diff line number Diff line
@@ -20,9 +20,9 @@ 
#include "comm.h"

#include "force.h"

#include "kspace.h"

#include "update.h"

#include "memory.h"

#include "neighbor.h"

#include "neigh_list.h"

#include "memory.h"

#include "error.h"



using namespace LAMMPS_NS;
@@ -66,20 +66,18 @@ PairBuckCoulLong::~PairBuckCoulLong() 


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

{

  int i,j,k,numneigh,itype,jtype;

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

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

  double rsq,r2inv,r6inv,forcecoul,forcebuck,fforce,factor_coul,factor_lj;

  double grij,expm2,prefactor,t,erfc;

  double factor,phicoul,phibuck,r,rexp;

  int *neighs;

  double **f;

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



  eng_vdwl = eng_coul = 0.0;

  if (vflag) for (i = 0; i < 6; i++) virial[i] = 0.0;



  if (vflag == 2) f = update->f_pair;

  else f = atom->f;

  double **x = atom->x;

  double **f = atom->f;

  double *q = atom->q;

  int *type = atom->type;

  int nlocal = atom->nlocal;
@@ -89,19 +87,25 @@ void PairBuckCoulLong::compute(int eflag, int vflag) 
  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 (i = 0; i < nlocal; i++) {

  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];

    neighs = neighbor->firstneigh[i];

    numneigh = neighbor->numneigh[i];

    jlist = firstneigh[i];

    jnum = numneigh[i];



    for (k = 0; k < numneigh; k++) {

      j = neighs[k];

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

      j = jlist[jj];



      if (j < nall) factor_coul = factor_lj = 1.0;

      else {
@@ -314,6 +318,8 @@ void PairBuckCoulLong::init_style() 
  else if (strcmp(force->kspace_style,"pppm") == 0)

    g_ewald = force->kspace->g_ewald;

  else error->all("Pair style is incompatible with KSpace style");



  int irequest = neighbor->request(this);

}



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

src/KSPACE/pair_buck_coul_long.h

+1 −1
Original line number Diff line number Diff line
@@ -25,8 +25,8 @@ class PairBuckCoulLong : public Pair { 
  void compute(int, int);

  void settings(int, char **);

  void coeff(int, char **);

  double init_one(int, int);

  void init_style();

  double init_one(int, int);

  void write_restart(FILE *);

  void read_restart(FILE *);

  void write_restart_settings(FILE *);

src/KSPACE/pair_coul_long.cpp

0 → 100644
+578 −0
Original line number Diff line number Diff 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: Paul Crozier (SNL)

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



#include "math.h"

#include "stdio.h"

#include "stdlib.h"

#include "string.h"

#include "pair_coul_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 MIN(a,b) ((a) < (b) ? (a) : (b))

#define MAX(a,b) ((a) > (b) ? (a) : (b))



#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



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



PairCoulLong::PairCoulLong(LAMMPS *lmp) : Pair(lmp)

{

  ftable = NULL;

}



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



PairCoulLong::~PairCoulLong()

{

  if (allocated) {

    memory->destroy_2d_int_array(setflag);

    memory->destroy_2d_double_array(cutsq);

  }

  if (ftable) free_tables();

}



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



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

{

  int i,j,ii,jj,inum,jnum,itable;

  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,fraction,table;

  double r,r2inv,forcecoul,fforce,factor_coul;

  double grij,expm2,prefactor,t,erfc;

  double factor,phicoul;

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

  float rsq;

  int *int_rsq = (int *) &rsq;



  eng_coul = 0.0;

  if (vflag) for (i = 0; i < 6; i++) virial[i] = 0.0;



  double **x = atom->x;

  double **f = atom->f;

  double *q = atom->q;

  int nlocal = atom->nlocal;

  int nall = atom->nlocal + atom->nghost;

  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];

    jlist = firstneigh[i];

    jnum = numneigh[i];



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

      j = jlist[jj];



      if (j < nall) factor_coul = 1.0;

      else {

	factor_coul = special_coul[j/nall];

	j %= nall;

      }



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

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

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

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



      if (rsq < cut_coulsq) {

	r2inv = 1.0/rsq;

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

	  r = sqrtf(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;

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

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

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

	} else {

	  itable = *int_rsq & ncoulmask;

	  itable >>= ncoulshiftbits;

	  fraction = (rsq - rtable[itable]) * drtable[itable];

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

	  forcecoul = qtmp*q[j] * table;

	  if (factor_coul < 1.0) {

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

	    prefactor = qtmp*q[j] * table;

	    forcecoul -= (1.0-factor_coul)*prefactor;

	  }

	}



	fforce = forcecoul * r2inv;



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

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

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

	if (newton_pair || j < nlocal) {

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

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

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

	}



	if (eflag) {

	  if (!ncoultablebits || rsq <= tabinnersq)

	    phicoul = prefactor*erfc;

	  else {

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

	    phicoul = qtmp*q[j] * table;

	  }

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

	  if (newton_pair || j < nlocal) eng_coul += phicoul;

	  else eng_coul += 0.5*phicoul;

	}



	if (vflag == 1) {

	  if (newton_pair == 0 && j >= nlocal) fforce *= 0.5;

	  virial[0] += delx*delx*fforce;

	  virial[1] += dely*dely*fforce;

	  virial[2] += delz*delz*fforce;

	  virial[3] += delx*dely*fforce;

	  virial[4] += delx*delz*fforce;

	  virial[5] += dely*delz*fforce;

	}

      }

    }

  }

  if (vflag == 2) virial_compute();

}

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

   allocate all arrays

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



void PairCoulLong::allocate()

{

  allocated = 1;

  int n = atom->ntypes;



  setflag = memory->create_2d_int_array(n+1,n+1,"pair:setflag");

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

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

      setflag[i][j] = 0;



  cutsq = memory->create_2d_double_array(n+1,n+1,"pair:cutsq");

}



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

   global settings

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



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

{

  if (narg != 1) error->all("Illegal pair_style command");



  cut_coul = atof(arg[0]);

}



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

   set coeffs for one or more type pairs

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



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

{

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

  if (!allocated) allocate();



  int ilo,ihi,jlo,jhi;

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

  force->bounds(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++) {

      setflag[i][j] = 1;

      count++;

    }

  }



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

}



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

   init specific to this pair style

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



void PairCoulLong::init_style()

{

  int i,j;



  if (!atom->q_flag)

    error->all("Pair style lj/cut/coul/long requires atom attribute q");



  int irequest = neighbor->request(this);



  cut_coulsq = cut_coul * cut_coul;



  // set & error check interior rRESPA cutoffs



  if (strcmp(update->integrate_style,"respa") == 0) {

    if (((Respa *) update->integrate)->level_inner >= 0) {

      cut_respa = ((Respa *) update->integrate)->cutoff;

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

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

	  if (cut_coul < cut_respa[3])

	    error->all("Pair cutoff < Respa interior cutoff");

    }

  } else cut_respa = NULL;



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



 if (force->kspace == NULL) 

    error->all("Pair style is incompatible with KSpace style");

  else if (strcmp(force->kspace_style,"ewald") == 0)

    g_ewald = force->kspace->g_ewald;

  else if (strcmp(force->kspace_style,"pppm") == 0)

    g_ewald = force->kspace->g_ewald;

  else error->all("Pair style is incompatible with KSpace style");



  // setup force tables



  if (ncoultablebits) init_tables();

}



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

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

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



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

{

  return cut_coul;

}



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

   setup force tables used in compute routines

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



void PairCoulLong::init_tables()

{

  int masklo,maskhi;

  double r,grij,expm2,derfc,rsw;

  double qqrd2e = force->qqrd2e;



  tabinnersq = tabinner*tabinner;

  init_bitmap(tabinner,cut_coul,ncoultablebits,

	      masklo,maskhi,ncoulmask,ncoulshiftbits);

  

  int ntable = 1;

  for (int i = 0; i < ncoultablebits; i++) ntable *= 2;

  

  // linear lookup tables of length N = 2^ncoultablebits

  // stored value = value at lower edge of bin

  // d values = delta from lower edge to upper edge of bin



  if (ftable) free_tables();

  

  rtable = (double *) memory->smalloc(ntable*sizeof(double),"pair:rtable");

  ftable = (double *) memory->smalloc(ntable*sizeof(double),"pair:ftable");

  ctable = (double *) memory->smalloc(ntable*sizeof(double),"pair:ctable");

  etable = (double *) memory->smalloc(ntable*sizeof(double),"pair:etable");

  drtable = (double *) memory->smalloc(ntable*sizeof(double),"pair:drtable");

  dftable = (double *) memory->smalloc(ntable*sizeof(double),"pair:dftable");

  dctable = (double *) memory->smalloc(ntable*sizeof(double),"pair:dctable");

  detable = (double *) memory->smalloc(ntable*sizeof(double),"pair:detable");



  if (cut_respa == NULL) {

    vtable = ptable = dvtable = dptable = NULL;

  } else {

    vtable = (double *) memory->smalloc(ntable*sizeof(double),"pair:vtable");

    ptable = (double *) memory->smalloc(ntable*sizeof(double),"pair:ptable");

    dvtable = (double *) memory->smalloc(ntable*sizeof(double),"pair:dvtable");

    dptable = (double *) memory->smalloc(ntable*sizeof(double),"pair:dptable");

  }



  float rsq;

  int *int_rsq = (int *) &rsq;  

  float minrsq;

  int *int_minrsq = (int *) &minrsq;

  int itablemin;

  *int_minrsq = 0 << ncoulshiftbits;

  *int_minrsq = *int_minrsq | maskhi;

    

  for (int i = 0; i < ntable; i++) {

    *int_rsq = i << ncoulshiftbits;

    *int_rsq = *int_rsq | masklo;

    if (rsq < tabinnersq) {

      *int_rsq = i << ncoulshiftbits;

      *int_rsq = *int_rsq | maskhi;

    }

    r = sqrtf(rsq);

    grij = g_ewald * r;

    expm2 = exp(-grij*grij);

    derfc = erfc(grij);

    if (cut_respa == NULL) {

      rtable[i] = rsq;

      ftable[i] = qqrd2e/r * (derfc + EWALD_F*grij*expm2);

      ctable[i] = qqrd2e/r;

      etable[i] = qqrd2e/r * derfc;

    } else {

      rtable[i] = rsq;

      ftable[i] = qqrd2e/r * (derfc + EWALD_F*grij*expm2 - 1.0);

      ctable[i] = 0.0;

      etable[i] = qqrd2e/r * derfc;

      ptable[i] = qqrd2e/r;

      vtable[i] = qqrd2e/r * (derfc + EWALD_F*grij*expm2);

      if (rsq > cut_respa[2]*cut_respa[2]) {

	if (rsq < cut_respa[3]*cut_respa[3]) {

	  rsw = (r - cut_respa[2])/(cut_respa[3] - cut_respa[2]); 

	  ftable[i] += qqrd2e/r * rsw*rsw*(3.0 - 2.0*rsw);

	  ctable[i] = qqrd2e/r * rsw*rsw*(3.0 - 2.0*rsw);

	} else {

	  ftable[i] = qqrd2e/r * (derfc + EWALD_F*grij*expm2);

	  ctable[i] = qqrd2e/r;

	}

      }

    }

    minrsq = MIN(minrsq,rsq);

  }



  tabinnersq = minrsq;

  

  int ntablem1 = ntable - 1;

  

  for (int i = 0; i < ntablem1; i++) {

    drtable[i] = 1.0/(rtable[i+1] - rtable[i]);

    dftable[i] = ftable[i+1] - ftable[i];

    dctable[i] = ctable[i+1] - ctable[i];

    detable[i] = etable[i+1] - etable[i];

  }



  if (cut_respa) {

    for (int i = 0; i < ntablem1; i++) {

      dvtable[i] = vtable[i+1] - vtable[i];

      dptable[i] = ptable[i+1] - ptable[i];

    }

  }

  

  // get the delta values for the last table entries 

  // tables are connected periodically between 0 and ntablem1

    

  drtable[ntablem1] = 1.0/(rtable[0] - rtable[ntablem1]);

  dftable[ntablem1] = ftable[0] - ftable[ntablem1];

  dctable[ntablem1] = ctable[0] - ctable[ntablem1];

  detable[ntablem1] = etable[0] - etable[ntablem1];

  if (cut_respa) {

    dvtable[ntablem1] = vtable[0] - vtable[ntablem1];

    dptable[ntablem1] = ptable[0] - ptable[ntablem1];

  }



  // get the correct delta values at itablemax    

  // smallest r is in bin itablemin

  // largest r is in bin itablemax, which is itablemin-1,

  //   or ntablem1 if itablemin=0

  // deltas at itablemax only needed if corresponding rsq < cut*cut

  // if so, compute deltas between rsq and cut*cut 

	

  double f_tmp,c_tmp,e_tmp,p_tmp,v_tmp;

  itablemin = *int_minrsq & ncoulmask;

  itablemin >>= ncoulshiftbits;  

  int itablemax = itablemin - 1; 

  if (itablemin == 0) itablemax = ntablem1;     

  *int_rsq = itablemax << ncoulshiftbits;

  *int_rsq = *int_rsq | maskhi;



  if (rsq < cut_coulsq) {

    rsq = cut_coulsq;  

    r = sqrtf(rsq);

    grij = g_ewald * r;

    expm2 = exp(-grij*grij);

    derfc = erfc(grij);



    if (cut_respa == NULL) {

      f_tmp = qqrd2e/r * (derfc + EWALD_F*grij*expm2);

      c_tmp = qqrd2e/r;

      e_tmp = qqrd2e/r * derfc;

    } else {

      f_tmp = qqrd2e/r * (derfc + EWALD_F*grij*expm2 - 1.0);

      c_tmp = 0.0;

      e_tmp = qqrd2e/r * derfc;

      p_tmp = qqrd2e/r;

      v_tmp = qqrd2e/r * (derfc + EWALD_F*grij*expm2);

      if (rsq > cut_respa[2]*cut_respa[2]) {

        if (rsq < cut_respa[3]*cut_respa[3]) {

          rsw = (r - cut_respa[2])/(cut_respa[3] - cut_respa[2]); 

          f_tmp += qqrd2e/r * rsw*rsw*(3.0 - 2.0*rsw);

          c_tmp = qqrd2e/r * rsw*rsw*(3.0 - 2.0*rsw);

        } else {

          f_tmp = qqrd2e/r * (derfc + EWALD_F*grij*expm2);

          c_tmp = qqrd2e/r;

        }

      }

    }



    drtable[itablemax] = 1.0/(rsq - rtable[itablemax]);   

    dftable[itablemax] = f_tmp - ftable[itablemax];

    dctable[itablemax] = c_tmp - ctable[itablemax];

    detable[itablemax] = e_tmp - etable[itablemax];

    if (cut_respa) {

      dvtable[itablemax] = v_tmp - vtable[itablemax];

      dptable[itablemax] = p_tmp - ptable[itablemax];

    }   

  }

}



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

  proc 0 writes to restart file

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



void PairCoulLong::write_restart(FILE *fp)

{

  write_restart_settings(fp);

}



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

  proc 0 reads from restart file, bcasts

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



void PairCoulLong::read_restart(FILE *fp)

{

  read_restart_settings(fp);



  allocate();

}



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

  proc 0 writes to restart file

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



void PairCoulLong::write_restart_settings(FILE *fp)

{

  fwrite(&cut_coul,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 PairCoulLong::read_restart_settings(FILE *fp)

{

  if (comm->me == 0) {

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

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

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

  }

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

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

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

}



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

   free memory for tables used in pair computations

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



void PairCoulLong::free_tables()

{

  memory->sfree(rtable);

  memory->sfree(drtable);

  memory->sfree(ftable);

  memory->sfree(dftable);

  memory->sfree(ctable);

  memory->sfree(dctable);

  memory->sfree(etable);

  memory->sfree(detable);

  memory->sfree(vtable);

  memory->sfree(dvtable);

  memory->sfree(ptable);

  memory->sfree(dptable);

}



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



void PairCoulLong::single(int i, int j, int itype, int jtype,

			       double rsq,

			       double factor_coul, double factor_lj,

			       int eflag, One &one)

{

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

  double fraction,table,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;

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

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

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

  } else {

    float rsq_single = rsq;

    int *int_rsq = (int *) &rsq_single;

    itable = *int_rsq & ncoulmask;

    itable >>= ncoulshiftbits;

    fraction = (rsq_single - 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;

    }

  }

  one.fforce = forcecoul * r2inv;

  

  if (eflag) {

    if (!ncoultablebits || rsq <= tabinnersq)

      phicoul = prefactor*erfc;

    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;

    one.eng_coul = phicoul;

    one.eng_vdwl = 0.0;

  }

}



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



void PairCoulLong::extract_long(double *p_cut_coul)

{

  *p_cut_coul = cut_coul;

}

src/KSPACE/pair_coul_long.h

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

   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.

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



#ifndef PAIR_COUL_LONG_H

#define PAIR_COUL_LONG_H



#include "pair.h"



namespace LAMMPS_NS {



class PairCoulLong : public Pair {

 public:

  PairCoulLong(class LAMMPS *);

  ~PairCoulLong();

  void compute(int, int);

  void settings(int, char **);

  void coeff(int, char **);

  void init_style();

  double init_one(int, int);

  void write_restart(FILE *);

  void read_restart(FILE *);

  void write_restart_settings(FILE *);

  void read_restart_settings(FILE *);

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



  void extract_long(double *);



 private:

  double cut_coul,cut_coulsq;

  double *cut_respa;

  double g_ewald;



  double tabinnersq;

  double *rtable,*drtable,*ftable,*dftable,*ctable,*dctable;

  double *etable,*detable,*ptable,*dptable,*vtable,*dvtable;

  int ncoulshiftbits,ncoulmask;



  void allocate();

  void init_tables();

  void free_tables();

};



}



#endif

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