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lammps/src/USER-CG-CMM/pair_cmm_common.cpp
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pair_cmm_common.cpp
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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.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Common functionality for the CMM coarse grained MD potentials.
Contributing author: Axel Kohlmeyer <akohlmey@gmail.com>
------------------------------------------------------------------------- */
#include "pair_cmm_common.h"
#include "memory.h"
#include "stdlib.h"
#include "string.h"
#include "ctype.h"
#include "math.h"
#include "math_const.h"
using namespace LAMMPS_NS;
using namespace MathConst;
#define SMALL 1.0e-6
/* ---------------------------------------------------------------------- */
PairCMMCommon::PairCMMCommon(class LAMMPS *lmp) : Pair(lmp)
{
ftable = NULL;
allocated_coul = 0;
kappa = 0.0;
respa_enable = 0;
single_enable = 0;
}
/* ---------------------------------------------------------------------- *
* clean up common arrays *
* ---------------------------------------------------------------------- */
PairCMMCommon::~PairCMMCommon() {
if (allocated) {
memory->destroy(setflag);
memory->destroy(cg_type);
memory->destroy(cut);
memory->destroy(cutsq);
memory->destroy(epsilon);
memory->destroy(sigma);
memory->destroy(offset);
memory->destroy(lj1);
memory->destroy(lj2);
memory->destroy(lj3);
memory->destroy(lj4);
allocated = 0;
}
}
/* ---------------------------------------------------------------------- *
* allocate common arrays *
* ---------------------------------------------------------------------- */
void PairCMMCommon::allocate()
{
allocated = 1;
int n = atom->ntypes;
memory->create(setflag,n+1,n+1,"paircg:setflag");
memory->create(cg_type,n+1,n+1,"paircg:cg_type");
for (int i = 1; i <= n; i++) {
for (int j = i; j <= n; j++) {
setflag[i][j] = 0;
cg_type[i][j] = CG_NOT_SET;
}
}
memory->create(cut,n+1,n+1,"paircg:cut");
memory->create(cutsq,n+1,n+1,"paircg:cutsq");
memory->create(epsilon,n+1,n+1,"paircg:epsilon");
memory->create(sigma,n+1,n+1,"paircg:sigma");
memory->create(offset,n+1,n+1,"paircg:offset");
memory->create(lj1,n+1,n+1,"paircg:lj1");
memory->create(lj2,n+1,n+1,"paircg:lj2");
memory->create(lj3,n+1,n+1,"paircg:lj3");
memory->create(lj4,n+1,n+1,"paircg:lj4");
}
/* ----------------------------------------------------------------------
global settings
------------------------------------------------------------------------- */
// arguments to the pair_style command (global version)
// args = cutoff (cutoff2 (kappa))
void PairCMMCommon::settings(int narg, char **arg)
{
if ((narg < 1) || (narg > 3)) error->all(FLERR,"Illegal pair_style command");
cut_lj_global = force->numeric(arg[0]);
if (narg == 1) cut_coul_global = cut_lj_global;
else cut_coul_global = force->numeric(arg[1]);
cut_coulsq_global = cut_coul_global*cut_coul_global;
// exponential coulomb screening (optional)
if (narg == 3) kappa = force->numeric(arg[2]);
if (fabs(kappa) < SMALL) kappa=0.0;
// reset cutoffs that have been explicitly set
if (allocated) {
int i,j;
for (i = 1; i <= atom->ntypes; i++) {
for (j = i+1; j <= atom->ntypes; j++) {
if (setflag[i][j]) {
cut[i][j] = cut_lj_global;
if (allocated_coul) {
cut[i][j] = MAX(cut_lj_global,cut_coul_global);
cut_lj[i][j] = cut_lj_global;
cut_coul[i][j] = cut_coul_global;
}
}
}
}
}
}
/* ----------------------------------------------------------------------
set coeffs for one or more type pairs
------------------------------------------------------------------------- */
void PairCMMCommon::coeff(int narg, char **arg)
{
if (narg < 5 || narg > 7) error->all(FLERR,"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 cg_type_one=find_cg_type(arg[2]);
if (cg_type_one == CG_NOT_SET) error->all(FLERR,"Error reading CG type flag.");
double epsilon_one = force->numeric(arg[3]);
double sigma_one = force->numeric(arg[4]);
double cut_lj_one = cut_lj_global;
double cut_coul_one = cut_coul_global;
if (narg >= 6) cut_lj_one = force->numeric(arg[5]);
if (narg == 7) cut_coul_one = force->numeric(arg[6]);
int count = 0;
for (int i = ilo; i <= ihi; i++) {
for (int j = MAX(jlo,i); j <= jhi; j++) {
cg_type[i][j] = cg_type_one;
epsilon[i][j] = epsilon_one;
sigma[i][j] = sigma_one;
setflag[i][j] = 1;
if (allocated_coul) {
cut_lj[i][j] = cut_lj_one;
cut_coul[i][j] = cut_coul_one;
} else {
cut[i][j] = cut_lj_one;
}
count++;
}
}
if (count == 0) error->all(FLERR,"Incorrect args for pair coefficients");
}
/* ----------------------------------------------------------------------
init specific to this pair style
------------------------------------------------------------------------- */
void PairCMMCommon::init_style()
{
// request regular or rRESPA neighbor lists
int irequest;
if (update->whichflag == 0 && strstr(update->integrate_style,"respa")) {
int respa = 0;
if (((Respa *) update->integrate)->level_inner >= 0) respa = 1;
if (((Respa *) update->integrate)->level_middle >= 0) respa = 2;
if (respa == 0) irequest = neighbor->request(this);
else if (respa == 1) {
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 1;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respainner = 1;
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 3;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respaouter = 1;
} else {
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 1;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respainner = 1;
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 2;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respamiddle = 1;
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 3;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respaouter = 1;
}
} else irequest = neighbor->request(this);
}
/* ----------------------------------------------------------------------
neighbor callback to inform pair style of neighbor list to use
regular or rRESPA
------------------------------------------------------------------------- */
void PairCMMCommon::init_list(int id, NeighList *ptr)
{
if (id == 0) list = ptr;
else if (id == 1) listinner = ptr;
else if (id == 2) listmiddle = ptr;
else if (id == 3) listouter = ptr;
}
/* ----------------------------------------------------------------------
init for one type pair i,j and corresponding j,i
------------------------------------------------------------------------- */
double PairCMMCommon::init_one(int i, int j)
{
if (setflag[i][j] == 0) {
error->all(FLERR,"for CG styles, epsilon and sigma need to be set explicitly for all pairs.");
}
const int cgt = cg_type[i][j];
if (cgt == CG_NOT_SET)
error->all(FLERR,"unrecognized LJ parameter flag");
lj1[i][j] = cg_prefact[cgt] * cg_pow1[cgt] * epsilon[i][j] * pow(sigma[i][j],cg_pow1[cgt]);
lj2[i][j] = cg_prefact[cgt] * cg_pow2[cgt] * epsilon[i][j] * pow(sigma[i][j],cg_pow2[cgt]);
lj3[i][j] = cg_prefact[cgt] * epsilon[i][j] * pow(sigma[i][j],cg_pow1[cgt]);
lj4[i][j] = cg_prefact[cgt] * epsilon[i][j] * pow(sigma[i][j],cg_pow2[cgt]);
double mycut = cut[i][j];
if (offset_flag) {
double ratio = sigma[i][j] / mycut;
offset[i][j] = cg_prefact[cgt] * epsilon[i][j] * (pow(ratio,cg_pow1[cgt]) - pow(ratio,cg_pow2[cgt]));
} else offset[i][j] = 0.0;
if (allocated_coul) {
mycut = MAX(cut_lj[i][j],cut_coul[i][j]);
cut[i][j] = mycut;
cut_ljsq[i][j]=cut_lj[i][j]*cut_lj[i][j];
cut_coulsq[i][j]=cut_coul[i][j]*cut_coul[i][j];
if (offset_flag) {
double ratio = sigma[i][j] / cut_lj[i][j];
offset[i][j] = cg_prefact[cgt] * epsilon[i][j] * (pow(ratio,cg_pow1[cgt]) - pow(ratio,cg_pow2[cgt]));
} else offset[i][j] = 0.0;
}
// make sure data is stored symmetrically
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];
cg_type[j][i] = cg_type[i][j];
cut[j][i] = mycut;
if (allocated_coul) {
cut_lj[j][i]=cut_lj[i][j];
cut_ljsq[j][i]=cut_ljsq[i][j];
cut_coul[j][i]=cut_coul[i][j];
cut_coulsq[j][i]=cut_coulsq[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) {
#if 1
error->all(FLERR,"tail correction not (yet) supported by CG potentials.");
#else
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 sig2 = sigma[i][j]*sigma[i][j];
double sig6 = sig2*sig2*sig2;
double rc3 = cut[i][j]*cut[i][j]*cut[i][j];
double rc6 = rc3*rc3;
double rc9 = rc3*rc6;
etail_ij = 8.0*MY_PI*all[0]*all[1]*epsilon[i][j] *
sig6 * (sig6 - 3.0*rc6) / (9.0*rc9);
ptail_ij = 16.0*MY_PI*all[0]*all[1]*epsilon[i][j] *
sig6 * (2.0*sig6 - 3.0*rc6) / (9.0*rc9);
#endif
}
return mycut;
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairCMMCommon::write_restart(FILE *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(&cg_type[i][j],sizeof(int),1,fp);
fwrite(&epsilon[i][j],sizeof(double),1,fp);
fwrite(&sigma[i][j],sizeof(double),1,fp);
fwrite(&cut[i][j],sizeof(double),1,fp);
if (allocated_coul) {
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 PairCMMCommon::read_restart(FILE *fp)
{
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(&cg_type[i][j],sizeof(int),1,fp);
fread(&epsilon[i][j],sizeof(double),1,fp);
fread(&sigma[i][j],sizeof(double),1,fp);
fread(&cut[i][j],sizeof(double),1,fp);
if(allocated_coul) {
fread(&cut_lj[i][j],sizeof(double),1,fp);
fread(&cut_coul[i][j],sizeof(double),1,fp);
}
}
MPI_Bcast(&cg_type[i][j],1,MPI_INT,0,world);
MPI_Bcast(&epsilon[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&sigma[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut[i][j],1,MPI_DOUBLE,0,world);
if (allocated_coul) {
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 PairCMMCommon::write_restart_settings(FILE *fp)
{
fwrite(&cut_lj_global,sizeof(double),1,fp);
fwrite(&cut_coul_global,sizeof(double),1,fp);
fwrite(&kappa,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 PairCMMCommon::read_restart_settings(FILE *fp)
{
int me = comm->me;
if (me == 0) {
fread(&cut_lj_global,sizeof(double),1,fp);
fread(&cut_coul_global,sizeof(double),1,fp);
fread(&kappa,sizeof(double),1,fp);
fread(&offset_flag,sizeof(int),1,fp);
fread(&mix_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(&kappa,1,MPI_DOUBLE,0,world);
MPI_Bcast(&offset_flag,1,MPI_INT,0,world);
MPI_Bcast(&mix_flag,1,MPI_INT,0,world);
cut_coulsq_global = cut_coul_global*cut_coul_global;
}
/* ---------------------------------------------------------------------- */
double PairCMMCommon::memory_usage()
{
double bytes=Pair::memory_usage();
int n = atom->ntypes;
// setflag/cg_type
bytes += (n+1)*(n+1)*sizeof(int)*2;
// cut/cutsq/epsilon/sigma/offset/lj1/lj2/lj3/lj4
bytes += (n+1)*(n+1)*sizeof(double)*9;
return bytes;
}
/* ------------------------------------------------------------------------ */
double PairCMMCommon::eval_single(int coul_type, int i, int j, int itype, int jtype,
double rsq, double factor_coul, double factor_lj,
double &fforce)
{
double lj_force, lj_erg, coul_force, coul_erg;
lj_force=lj_erg=coul_force=coul_erg=0.0;
if (rsq < cut_ljsq[itype][jtype]) {
const int cgt = cg_type[itype][jtype];
const double cgpow1 = cg_pow1[cgt];
const double cgpow2 = cg_pow2[cgt];
const double cgpref = cg_prefact[cgt];
const double ratio = sigma[itype][jtype]/sqrt(rsq);
const double eps = epsilon[itype][jtype];
lj_force = cgpref*eps * (cgpow1*pow(ratio,cgpow1)
- cgpow2*pow(ratio,cgpow2))/rsq;
lj_erg = cgpref*eps * (pow(ratio,cgpow1) - pow(ratio,cgpow2));
}
if (rsq < cut_coul[itype][jtype]) {
if(coul_type == CG_COUL_LONG) {
error->all(FLERR,"single energy computation with long-range coulomb not supported by CG potentials.");
} else if ((coul_type == CG_COUL_CUT) || (coul_type == CG_COUL_DEBYE)) {
const double r2inv = 1.0/rsq;
const double rinv = sqrt(r2inv);
const double qscreen=exp(-kappa*sqrt(rsq));
coul_force = force->qqrd2e * atom->q[i]*atom->q[j]*rinv * qscreen * (kappa + rinv);
coul_erg = force->qqrd2e * atom->q[i]*atom->q[j]*rinv * qscreen;
// error->all(FLERR,"single energy computation with coulomb not supported by CG potentials.");
} else if (coul_type == CG_COUL_NONE) {
; // do nothing
} else {
error->all(FLERR,"unknown coulomb type with CG potentials.");
}
}
fforce = factor_lj*lj_force + factor_coul*coul_force;
return factor_lj*lj_erg + factor_coul*coul_erg;
}
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