Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F64256377
pair_lj_class2_coul_cut.cpp
No One
Temporary
Actions
Download File
Edit File
Delete File
View Transforms
Subscribe
Mute Notifications
Award Token
Subscribers
None
File Metadata
Details
File Info
Storage
Attached
Created
Sat, May 25, 16:22
Size
14 KB
Mime Type
text/x-c
Expires
Mon, May 27, 16:22 (2 d)
Engine
blob
Format
Raw Data
Handle
17866577
Attached To
rLAMMPS lammps
pair_lj_class2_coul_cut.cpp
View Options
/* ----------------------------------------------------------------------
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.
------------------------------------------------------------------------- */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "pair_lj_class2_coul_cut.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "math_const.h"
#include "memory.h"
#include "error.h"
using namespace LAMMPS_NS;
using namespace MathConst;
/* ---------------------------------------------------------------------- */
PairLJClass2CoulCut::PairLJClass2CoulCut(LAMMPS *lmp) : Pair(lmp)
{
writedata = 1;
}
/* ---------------------------------------------------------------------- */
PairLJClass2CoulCut::~PairLJClass2CoulCut()
{
if (!copymode) {
if (allocated) {
memory->destroy(setflag);
memory->destroy(cutsq);
memory->destroy(cut_lj);
memory->destroy(cut_ljsq);
memory->destroy(cut_coul);
memory->destroy(cut_coulsq);
memory->destroy(epsilon);
memory->destroy(sigma);
memory->destroy(lj1);
memory->destroy(lj2);
memory->destroy(lj3);
memory->destroy(lj4);
memory->destroy(offset);
}
}
}
/* ---------------------------------------------------------------------- */
void PairLJClass2CoulCut::compute(int eflag, int vflag)
{
int i,j,ii,jj,inum,jnum,itype,jtype;
double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
double rsq,rinv,r2inv,r3inv,r6inv,forcecoul,forcelj;
double factor_coul,factor_lj;
int *ilist,*jlist,*numneigh,**firstneigh;
evdwl = 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;
double *special_lj = force->special_lj;
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_lj = special_lj[sbmask(j)];
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;
if (rsq < cut_coulsq[itype][jtype])
forcecoul = qqrd2e * qtmp*q[j]*sqrt(r2inv);
else forcecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
rinv = sqrt(r2inv);
r3inv = r2inv*rinv;
r6inv = r3inv*r3inv;
forcelj = r6inv * (lj1[itype][jtype]*r3inv - lj2[itype][jtype]);
} else forcelj = 0.0;
fpair = (factor_coul*forcecoul + factor_lj*forcelj) * 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 (rsq < cut_coulsq[itype][jtype])
ecoul = factor_coul * qqrd2e * qtmp*q[j]*sqrt(r2inv);
else ecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
evdwl = r6inv*(lj3[itype][jtype]*r3inv-lj4[itype][jtype]) -
offset[itype][jtype];
evdwl *= factor_lj;
} else evdwl = 0.0;
}
if (evflag) ev_tally(i,j,nlocal,newton_pair,
evdwl,ecoul,fpair,delx,dely,delz);
}
}
}
if (vflag_fdotr) virial_fdotr_compute();
}
/* ----------------------------------------------------------------------
allocate all arrays
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::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(cut_lj,n+1,n+1,"pair:cut_lj");
memory->create(cut_ljsq,n+1,n+1,"pair:cut_ljsq");
memory->create(cut_coul,n+1,n+1,"pair:cut_coul");
memory->create(cut_coulsq,n+1,n+1,"pair:cut_coulsq");
memory->create(epsilon,n+1,n+1,"pair:epsilon");
memory->create(sigma,n+1,n+1,"pair:sigma");
memory->create(lj1,n+1,n+1,"pair:lj1");
memory->create(lj2,n+1,n+1,"pair:lj2");
memory->create(lj3,n+1,n+1,"pair:lj3");
memory->create(lj4,n+1,n+1,"pair:lj4");
memory->create(offset,n+1,n+1,"pair:offset");
}
/* ----------------------------------------------------------------------
global settings
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::settings(int narg, char **arg)
{
if (narg < 1 || narg > 2) error->all(FLERR,"Illegal pair_style command");
cut_lj_global = force->numeric(FLERR,arg[0]);
if (narg == 1) cut_coul_global = cut_lj_global;
else cut_coul_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_lj[i][j] = cut_lj_global;
cut_coul[i][j] = cut_coul_global;
}
}
}
/* ----------------------------------------------------------------------
set coeffs for one or more type pairs
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::coeff(int narg, char **arg)
{
if (narg < 4 || narg > 6) 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);
double epsilon_one = force->numeric(FLERR,arg[2]);
double sigma_one = force->numeric(FLERR,arg[3]);
double cut_lj_one = cut_lj_global;
double cut_coul_one = cut_coul_global;
if (narg >= 5) cut_coul_one = cut_lj_one = force->numeric(FLERR,arg[4]);
if (narg == 6) cut_coul_one = force->numeric(FLERR,arg[5]);
int count = 0;
for (int i = ilo; i <= ihi; i++) {
for (int j = MAX(jlo,i); j <= jhi; j++) {
epsilon[i][j] = epsilon_one;
sigma[i][j] = sigma_one;
cut_lj[i][j] = cut_lj_one;
cut_coul[i][j] = cut_coul_one;
setflag[i][j] = 1;
count++;
}
}
if (count == 0) error->all(FLERR,"Incorrect args for pair coefficients");
}
/* ----------------------------------------------------------------------
init specific to this pair style
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::init_style()
{
if (!atom->q_flag)
error->all(FLERR,"Pair style lj/class2/coul/cut requires atom attribute q");
neighbor->request(this,instance_me);
}
/* ----------------------------------------------------------------------
init for one type pair i,j and corresponding j,i
------------------------------------------------------------------------- */
double PairLJClass2CoulCut::init_one(int i, int j)
{
// always mix epsilon,sigma via sixthpower rules
// mix distance via user-defined rule
if (setflag[i][j] == 0) {
epsilon[i][j] = 2.0 * sqrt(epsilon[i][i]*epsilon[j][j]) *
pow(sigma[i][i],3.0) * pow(sigma[j][j],3.0) /
(pow(sigma[i][i],6.0) + pow(sigma[j][j],6.0));
sigma[i][j] =
pow((0.5 * (pow(sigma[i][i],6.0) + pow(sigma[j][j],6.0))),1.0/6.0);
cut_lj[i][j] = mix_distance(cut_lj[i][i],cut_lj[j][j]);
cut_coul[i][j] = mix_distance(cut_coul[i][i],cut_coul[j][j]);
}
double cut = MAX(cut_lj[i][j],cut_coul[i][j]);
cut_ljsq[i][j] = cut_lj[i][j] * cut_lj[i][j];
cut_coulsq[i][j] = cut_coul[i][j] * cut_coul[i][j];
lj1[i][j] = 18.0 * epsilon[i][j] * pow(sigma[i][j],9.0);
lj2[i][j] = 18.0 * epsilon[i][j] * pow(sigma[i][j],6.0);
lj3[i][j] = 2.0 * epsilon[i][j] * pow(sigma[i][j],9.0);
lj4[i][j] = 3.0 * epsilon[i][j] * pow(sigma[i][j],6.0);
if (offset_flag && (cut_lj[i][j] > 0.0)) {
double ratio = sigma[i][j] / cut_lj[i][j];
offset[i][j] = epsilon[i][j] * (2.0*pow(ratio,9.0) - 3.0*pow(ratio,6.0));
} else offset[i][j] = 0.0;
cut_ljsq[j][i] = cut_ljsq[i][j];
cut_coulsq[j][i] = cut_coulsq[i][j];
lj1[j][i] = lj1[i][j];
lj2[j][i] = lj2[i][j];
lj3[j][i] = lj3[i][j];
lj4[j][i] = lj4[i][j];
offset[j][i] = offset[i][j];
// compute I,J contribution to long-range tail correction
// count total # of atoms of type I and J via Allreduce
if (tail_flag) {
int *type = atom->type;
int nlocal = atom->nlocal;
double count[2],all[2];
count[0] = count[1] = 0.0;
for (int k = 0; k < nlocal; k++) {
if (type[k] == i) count[0] += 1.0;
if (type[k] == j) count[1] += 1.0;
}
MPI_Allreduce(count,all,2,MPI_DOUBLE,MPI_SUM,world);
double sig3 = sigma[i][j]*sigma[i][j]*sigma[i][j];
double sig6 = sig3*sig3;
double rc3 = cut_lj[i][j]*cut_lj[i][j]*cut_lj[i][j];
double rc6 = rc3*rc3;
etail_ij = 2.0*MY_PI*all[0]*all[1]*epsilon[i][j] *
sig6 * (sig3 - 3.0*rc3) / (3.0*rc6);
ptail_ij = 2.0*MY_PI*all[0]*all[1]*epsilon[i][j] *
sig6 * (sig3 - 2.0*rc3) / rc6;
}
return cut;
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::write_restart(FILE *fp)
{
write_restart_settings(fp);
int i,j;
for (i = 1; i <= atom->ntypes; i++)
for (j = i; j <= atom->ntypes; j++) {
fwrite(&setflag[i][j],sizeof(int),1,fp);
if (setflag[i][j]) {
fwrite(&epsilon[i][j],sizeof(double),1,fp);
fwrite(&sigma[i][j],sizeof(double),1,fp);
fwrite(&cut_lj[i][j],sizeof(double),1,fp);
fwrite(&cut_coul[i][j],sizeof(double),1,fp);
}
}
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::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(&epsilon[i][j],sizeof(double),1,fp);
fread(&sigma[i][j],sizeof(double),1,fp);
fread(&cut_lj[i][j],sizeof(double),1,fp);
fread(&cut_coul[i][j],sizeof(double),1,fp);
}
MPI_Bcast(&epsilon[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&sigma[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut_lj[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut_coul[i][j],1,MPI_DOUBLE,0,world);
}
}
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::write_restart_settings(FILE *fp)
{
fwrite(&cut_lj_global,sizeof(double),1,fp);
fwrite(&cut_coul_global,sizeof(double),1,fp);
fwrite(&offset_flag,sizeof(int),1,fp);
fwrite(&mix_flag,sizeof(int),1,fp);
fwrite(&tail_flag,sizeof(int),1,fp);
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::read_restart_settings(FILE *fp)
{
if (comm->me == 0) {
fread(&cut_lj_global,sizeof(double),1,fp);
fread(&cut_coul_global,sizeof(double),1,fp);
fread(&offset_flag,sizeof(int),1,fp);
fread(&mix_flag,sizeof(int),1,fp);
fread(&tail_flag,sizeof(int),1,fp);
}
MPI_Bcast(&cut_lj_global,1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut_coul_global,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(&tail_flag,1,MPI_INT,0,world);
}
/* ----------------------------------------------------------------------
proc 0 writes to data file
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::write_data(FILE *fp)
{
for (int i = 1; i <= atom->ntypes; i++)
fprintf(fp,"%d %g %g\n",i,epsilon[i][i],sigma[i][i]);
}
/* ----------------------------------------------------------------------
proc 0 writes all pairs to data file
------------------------------------------------------------------------- */
void PairLJClass2CoulCut::write_data_all(FILE *fp)
{
for (int i = 1; i <= atom->ntypes; i++)
for (int j = i; j <= atom->ntypes; j++)
fprintf(fp,"%d %d %g %g %g\n",i,j,epsilon[i][j],sigma[i][j],cut_lj[i][j]);
}
/* ---------------------------------------------------------------------- */
double PairLJClass2CoulCut::single(int i, int j, int itype, int jtype,
double rsq,
double factor_coul, double factor_lj,
double &fforce)
{
double r2inv,rinv,r3inv,r6inv,forcecoul,forcelj,phicoul,philj;
r2inv = 1.0/rsq;
if (rsq < cut_coulsq[itype][jtype])
forcecoul = force->qqrd2e * atom->q[i]*atom->q[j]*sqrt(r2inv);
else forcecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
rinv = sqrt(r2inv);
r3inv = r2inv*rinv;
r6inv = r3inv*r3inv;
forcelj = r6inv * (lj1[itype][jtype]*r3inv - lj2[itype][jtype]);
} else forcelj = 0.0;
fforce = (factor_coul*forcecoul + factor_lj*forcelj) * r2inv;
double eng = 0.0;
if (rsq < cut_coulsq[itype][jtype]) {
phicoul = force->qqrd2e * atom->q[i]*atom->q[j]*sqrt(r2inv);
eng += factor_coul*phicoul;
}
if (rsq < cut_ljsq[itype][jtype]) {
philj = r6inv*(lj3[itype][jtype]*r3inv-lj4[itype][jtype]) -
offset[itype][jtype];
eng += factor_lj*philj;
}
return eng;
}
Event Timeline
Log In to Comment