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1ed25d195be0d32caa75f99172dcda48afab95ed
lammps/src/SPIN/pair_spin_dmi.cpp
Axel Kohlmeyer 1ed25d195b convert c-style includes for c-library calls to c++-style
2018-07-10 09:48:49 -04:00

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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.
------------------------------------------------------------------------- */
/* ------------------------------------------------------------------------
Contributing authors: Julien Tranchida (SNL)
Aidan Thompson (SNL)
Please cite the related publication:
Tranchida, J., Plimpton, S. J., Thibaudeau, P., & Thompson, A. P. (2018).
Massively parallel symplectic algorithm for coupled magnetic spin dynamics
and molecular dynamics. Journal of Computational Physics.
------------------------------------------------------------------------- */
#include <cmath>
#include <cstdlib>
#include <cstring>
#include "atom.h"
#include "comm.h"
#include "error.h"
#include "force.h"
#include "fix.h"
#include "fix_nve_spin.h"
#include "pair_hybrid.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "neigh_request.h"
#include "math_const.h"
#include "memory.h"
#include "modify.h"
#include "pair_spin_dmi.h"
#include "update.h"
using namespace LAMMPS_NS;
using namespace MathConst;
/* ---------------------------------------------------------------------- */
PairSpinDmi::PairSpinDmi(LAMMPS *lmp) : PairSpin(lmp),
lockfixnvespin(NULL)
{
single_enable = 0;
no_virial_fdotr_compute = 1;
lattice_flag = 0;
}
/* ---------------------------------------------------------------------- */
PairSpinDmi::~PairSpinDmi()
{
if (allocated) {
memory->destroy(setflag);
memory->destroy(cut_spin_dmi);
memory->destroy(DM);
memory->destroy(v_dmx);
memory->destroy(v_dmy);
memory->destroy(v_dmz);
memory->destroy(cutsq);
}
}
/* ----------------------------------------------------------------------
global settings
------------------------------------------------------------------------- */
void PairSpinDmi::settings(int narg, char **arg)
{
if (narg < 1 || narg > 2)
error->all(FLERR,"Incorrect number of args in pair/spin/dmi command");
if (strcmp(update->unit_style,"metal") != 0)
error->all(FLERR,"Spin simulations require metal unit style");
cut_spin_dmi_global = force->numeric(FLERR,arg[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_spin_dmi[i][j] = cut_spin_dmi_global;
}
}
}
}
}
/* ----------------------------------------------------------------------
set coeffs for one or more type spin pairs (only one for now)
------------------------------------------------------------------------- */
void PairSpinDmi::coeff(int narg, char **arg)
{
if (!allocated) allocate();
// check if args correct
if (strcmp(arg[2],"dmi") != 0)
error->all(FLERR,"Incorrect args in pair_style command");
if (narg != 8)
error->all(FLERR,"Incorrect args in pair_style command");
int ilo,ihi,jlo,jhi;
force->bounds(FLERR,arg[0],atom->ntypes,ilo,ihi);
force->bounds(FLERR,arg[1],atom->ntypes,jlo,jhi);
const double rij = force->numeric(FLERR,arg[3]);
const double dm = (force->numeric(FLERR,arg[4]))/hbar;
double dmx = force->numeric(FLERR,arg[5]);
double dmy = force->numeric(FLERR,arg[6]);
double dmz = force->numeric(FLERR,arg[7]);
double inorm = 1.0/(dmx*dmx+dmy*dmy+dmz*dmz);
dmx *= inorm;
dmy *= inorm;
dmz *= inorm;
int count = 0;
for (int i = ilo; i <= ihi; i++) {
for (int j = MAX(jlo,i); j <= jhi; j++) {
cut_spin_dmi[i][j] = rij;
DM[i][j] = dm;
v_dmx[i][j] = dmx * dm;
v_dmy[i][j] = dmy * dm;
v_dmz[i][j] = dmz * dm;
setflag[i][j] = 1;
count++;
}
}
if (count == 0)
error->all(FLERR,"Incorrect args in pair_style command");
}
/* ----------------------------------------------------------------------
init specific to this pair style
------------------------------------------------------------------------- */
void PairSpinDmi::init_style()
{
if (!atom->sp_flag)
error->all(FLERR,"Pair spin requires atom/spin style");
// need a full neighbor list
int irequest = neighbor->request(this,instance_me);
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->full = 1;
// checking if nve/spin is a listed fix
int ifix = 0;
while (ifix < modify->nfix) {
if (strcmp(modify->fix[ifix]->style,"nve/spin") == 0) break;
ifix++;
}
if (ifix == modify->nfix)
error->all(FLERR,"pair/spin style requires nve/spin");
// get the lattice_flag from nve/spin
for (int i = 0; i < modify->nfix; i++) {
if (strcmp(modify->fix[i]->style,"nve/spin") == 0) {
lockfixnvespin = (FixNVESpin *) modify->fix[i];
lattice_flag = lockfixnvespin->lattice_flag;
}
}
}
/* ----------------------------------------------------------------------
init for one type pair i,j and corresponding j,i
------------------------------------------------------------------------- */
double PairSpinDmi::init_one(int i, int j)
{
if (setflag[i][j] == 0) error->all(FLERR,"All pair coeffs are not set");
return cut_spin_dmi_global;
}
/* ----------------------------------------------------------------------
extract the larger cutoff
------------------------------------------------------------------------- */
void *PairSpinDmi::extract(const char *str, int &dim)
{
dim = 0;
if (strcmp(str,"cut") == 0) return (void *) &cut_spin_dmi_global;
return NULL;
}
/* ---------------------------------------------------------------------- */
void PairSpinDmi::compute(int eflag, int vflag)
{
int i,j,ii,jj,inum,jnum,itype,jtype;
double evdwl, ecoul;
double xi[3], rij[3], eij[3];
double spi[3], spj[3];
double fi[3], fmi[3];
double local_cut2;
double rsq, inorm;
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 **fm = atom->fm;
double **sp = atom->sp;
int *type = atom->type;
int nlocal = atom->nlocal;
int newton_pair = force->newton_pair;
inum = list->inum;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
// dmi computation
// loop over all atoms
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
itype = type[i];
jlist = firstneigh[i];
jnum = numneigh[i];
xi[0] = x[i][0];
xi[1] = x[i][1];
xi[2] = x[i][2];
spi[0] = sp[i][0];
spi[1] = sp[i][1];
spi[2] = sp[i][2];
// loop on neighbors
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
j &= NEIGHMASK;
jtype = type[j];
spj[0] = sp[j][0];
spj[1] = sp[j][1];
spj[2] = sp[j][2];
evdwl = 0.0;
fi[0] = fi[1] = fi[2] = 0.0;
fmi[0] = fmi[1] = fmi[2] = 0.0;
rij[0] = rij[1] = rij[2] = 0.0;
eij[0] = eij[1] = eij[2] = 0.0;
rij[0] = x[j][0] - xi[0];
rij[1] = x[j][1] - xi[1];
rij[2] = x[j][2] - xi[2];
rsq = rij[0]*rij[0] + rij[1]*rij[1] + rij[2]*rij[2];
inorm = 1.0/sqrt(rsq);
eij[0] = rij[0]*inorm;
eij[1] = rij[1]*inorm;
eij[2] = rij[2]*inorm;
local_cut2 = cut_spin_dmi[itype][jtype]*cut_spin_dmi[itype][jtype];
// compute dmi interaction
if (rsq <= local_cut2) {
compute_dmi(i,j,eij,fmi,spj);
if (lattice_flag) {
compute_dmi_mech(fi);
}
}
f[i][0] += fi[0];
f[i][1] += fi[1];
f[i][2] += fi[2];
fm[i][0] += fmi[0];
fm[i][1] += fmi[1];
fm[i][2] += fmi[2];
if (newton_pair || j < nlocal) {
f[j][0] -= fi[0];
f[j][1] -= fi[1];
f[j][2] -= fi[2];
}
if (eflag) {
evdwl -= (spi[0]*fmi[0] + spi[1]*fmi[1] + spi[2]*fmi[2]);
evdwl *= hbar;
} else evdwl = 0.0;
if (evflag) ev_tally_xyz(i,j,nlocal,newton_pair,
evdwl,ecoul,fi[0],fi[1],fi[2],rij[0],rij[1],rij[2]);
}
}
if (vflag_fdotr) virial_fdotr_compute();
}
/* ---------------------------------------------------------------------- */
void PairSpinDmi::compute_single_pair(int ii, double fmi[3])
{
int *type = atom->type;
double **x = atom->x;
double **sp = atom->sp;
double local_cut2;
double xi[3], rij[3], eij[3];
double spj[3];
int i,j,jnum,itype,jtype;
int *ilist,*jlist,*numneigh,**firstneigh;
double rsq, inorm;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
i = ilist[ii];
itype = type[i];
xi[0] = x[i][0];
xi[1] = x[i][1];
xi[2] = x[i][2];
jlist = firstneigh[i];
jnum = numneigh[i];
for (int jj = 0; jj < jnum; jj++) {
j = jlist[jj];
j &= NEIGHMASK;
jtype = type[j];
spj[0] = sp[j][0];
spj[1] = sp[j][1];
spj[2] = sp[j][2];
rij[0] = x[j][0] - xi[0];
rij[1] = x[j][1] - xi[1];
rij[2] = x[j][2] - xi[2];
rsq = rij[0]*rij[0] + rij[1]*rij[1] + rij[2]*rij[2];
inorm = 1.0/sqrt(rsq);
eij[0] = rij[0]*inorm;
eij[1] = rij[1]*inorm;
eij[2] = rij[2]*inorm;
local_cut2 = cut_spin_dmi[itype][jtype]*cut_spin_dmi[itype][jtype];
if (rsq <= local_cut2) {
compute_dmi(i,j,eij,fmi,spj);
}
}
}
/* ----------------------------------------------------------------------
compute the dmi interaction between spin i and spin j
------------------------------------------------------------------------- */
void PairSpinDmi::compute_dmi(int i, int j, double eij[3], double fmi[3], double spj[3])
{
int *type = atom->type;
int itype, jtype;
double dmix, dmiy, dmiz;
itype = type[i];
jtype = type[j];
dmix = eij[1]*v_dmz[itype][jtype] - eij[2]*v_dmy[itype][jtype];
dmiy = eij[2]*v_dmx[itype][jtype] - eij[2]*v_dmz[itype][jtype];
dmiz = eij[0]*v_dmy[itype][jtype] - eij[1]*v_dmx[itype][jtype];
fmi[0] += (spj[1]*dmiz - spj[2]*dmiy);
fmi[1] += (spj[2]*dmix - spj[0]*dmiz);
fmi[2] += (spj[0]*dmiy - spj[1]*dmix);
}
/* ----------------------------------------------------------------------
compute the mechanical force due to the dmi interaction between atom i and atom j
------------------------------------------------------------------------- */
void PairSpinDmi::compute_dmi_mech(double fi[3])
{
fi[0] += 0.0;
fi[1] += 0.0;
fi[2] += 0.0;
}
/* ----------------------------------------------------------------------
allocate all arrays
------------------------------------------------------------------------- */
void PairSpinDmi::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(cut_spin_dmi,n+1,n+1,"pair:cut_spin_dmi");
memory->create(DM,n+1,n+1,"pair:DM");
memory->create(v_dmx,n+1,n+1,"pair:DM_vector_x");
memory->create(v_dmy,n+1,n+1,"pair:DM_vector_y");
memory->create(v_dmz,n+1,n+1,"pair:DM_vector_z");
memory->create(cutsq,n+1,n+1,"pair:cutsq");
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairSpinDmi::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(&DM[i][j],sizeof(double),1,fp);
fwrite(&v_dmx[i][j],sizeof(double),1,fp);
fwrite(&v_dmy[i][j],sizeof(double),1,fp);
fwrite(&v_dmz[i][j],sizeof(double),1,fp);
fwrite(&cut_spin_dmi[i][j],sizeof(double),1,fp);
}
}
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairSpinDmi::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(&DM[i][j],sizeof(double),1,fp);
fread(&v_dmx[i][j],sizeof(double),1,fp);
fread(&v_dmy[i][j],sizeof(double),1,fp);
fread(&v_dmz[i][j],sizeof(double),1,fp);
fread(&cut_spin_dmi[i][j],sizeof(double),1,fp);
}
MPI_Bcast(&DM[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&v_dmx[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&v_dmy[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&v_dmz[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut_spin_dmi[i][j],1,MPI_DOUBLE,0,world);
}
}
}
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairSpinDmi::write_restart_settings(FILE *fp)
{
fwrite(&cut_spin_dmi_global,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 PairSpinDmi::read_restart_settings(FILE *fp)
{
if (comm->me == 0) {
fread(&cut_spin_dmi_global,sizeof(double),1,fp);
fread(&offset_flag,sizeof(int),1,fp);
fread(&mix_flag,sizeof(int),1,fp);
}
MPI_Bcast(&cut_spin_dmi_global,1,MPI_DOUBLE,0,world);
MPI_Bcast(&offset_flag,1,MPI_INT,0,world);
MPI_Bcast(&mix_flag,1,MPI_INT,0,world);
}
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