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pair_cdeam_omp.cpp
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Sun, Sep 1, 21:02

pair_cdeam_omp.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
This software is distributed under the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing author: Axel Kohlmeyer (Temple U)
------------------------------------------------------------------------- */
#include <math.h>
#include <string.h>
#include "pair_cdeam_omp.h"
#include "atom.h"
#include "comm.h"
#include "error.h"
#include "force.h"
#include "memory.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "suffix.h"
using namespace LAMMPS_NS;
// This is for debugging purposes. The ASSERT() macro is used in the code to check
// if everything runs as expected. Change this to #if 0 if you don't need the checking.
#if 0
#define ASSERT(cond) ((!(cond)) ? my_failure(error,__FILE__,__LINE__) : my_noop())
inline void my_noop() {}
inline void my_failure(Error* error, const char* file, int line) {
char str[1024];
sprintf(str,"Assertion failure: File %s, line %i", file, line);
error->one(FLERR,str);
}
#else
#define ASSERT(cond)
#endif
/* ---------------------------------------------------------------------- */
PairCDEAMOMP::PairCDEAMOMP(LAMMPS *lmp, int _cdeamVersion) :
PairEAM(lmp), PairCDEAM(lmp,_cdeamVersion), ThrOMP(lmp, THR_PAIR)
{
suffix_flag |= Suffix::OMP;
respa_enable = 0;
}
/* ---------------------------------------------------------------------- */
void PairCDEAMOMP::compute(int eflag, int vflag)
{
if (eflag || vflag) {
ev_setup(eflag,vflag);
} else evflag = vflag_fdotr = eflag_global = eflag_atom = 0;
const int nall = atom->nlocal + atom->nghost;
const int nthreads = comm->nthreads;
const int inum = list->inum;
// grow energy and fp arrays if necessary
// need to be atom->nmax in length
if (atom->nmax > nmax) {
memory->destroy(rho);
memory->destroy(rhoB);
memory->destroy(D_values);
memory->destroy(fp);
nmax = atom->nmax;
memory->create(rho,nthreads*nmax,"pair:rho");
memory->create(rhoB,nthreads*nmax,"pair:mu");
memory->create(D_values,nthreads*nmax,"pair:D_values");
memory->create(fp,nmax,"pair:fp");
}
#if defined(_OPENMP)
#pragma omp parallel default(none) shared(eflag,vflag)
#endif
{
int ifrom, ito, tid;
loop_setup_thr(ifrom, ito, tid, inum, nthreads);
ThrData *thr = fix->get_thr(tid);
thr->timer(Timer::START);
ev_setup_thr(eflag, vflag, nall, eatom, vatom, thr);
if (force->newton_pair)
thr->init_cdeam(nall, rho, rhoB, D_values);
else
thr->init_cdeam(atom->nlocal, rho, rhoB, D_values);
switch (cdeamVersion) {
case 1:
if (evflag) {
if (eflag) {
if (force->newton_pair) eval<1,1,1,1>(ifrom, ito, thr);
else eval<1,1,0,1>(ifrom, ito, thr);
} else {
if (force->newton_pair) eval<1,0,1,1>(ifrom, ito, thr);
else eval<1,0,0,1>(ifrom, ito, thr);
}
} else {
if (force->newton_pair) eval<0,0,1,1>(ifrom, ito, thr);
else eval<0,0,0,1>(ifrom, ito, thr);
}
break;
case 2:
if (evflag) {
if (eflag) {
if (force->newton_pair) eval<1,1,1,2>(ifrom, ito, thr);
else eval<1,1,0,2>(ifrom, ito, thr);
} else {
if (force->newton_pair) eval<1,0,1,2>(ifrom, ito, thr);
else eval<1,0,0,2>(ifrom, ito, thr);
}
} else {
if (force->newton_pair) eval<0,0,1,2>(ifrom, ito, thr);
else eval<0,0,0,2>(ifrom, ito, thr);
}
break;
default:
{
#if defined(_OPENMP)
#pragma omp master
#endif
error->all(FLERR,"unsupported eam/cd pair style variant");
}
}
thr->timer(Timer::PAIR);
reduce_thr(this, eflag, vflag, thr);
} // end of omp parallel region
}
template <int EVFLAG, int EFLAG, int NEWTON_PAIR, int CDEAMVERSION>
void PairCDEAMOMP::eval(int iifrom, int iito, ThrData * const thr)
{
int i,j,ii,jj,jnum,itype,jtype;
double xtmp,ytmp,ztmp,delx,dely,delz,evdwl,fpair;
double rsq,rhoip,rhojp,recip,phi;
int *ilist,*jlist,*numneigh,**firstneigh;
evdwl = 0.0;
const dbl3_t * _noalias const x = (dbl3_t *) atom->x[0];
dbl3_t * _noalias const f = (dbl3_t *) thr->get_f()[0];
double * const rho_t = thr->get_rho();
double * const rhoB_t = thr->get_rhoB();
double * const D_values_t = thr->get_D_values();
const int tid = thr->get_tid();
const int nthreads = comm->nthreads;
const int * _noalias const type = atom->type;
const int nlocal = atom->nlocal;
const int nall = nlocal + atom->nghost;
double fxtmp,fytmp,fztmp;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
// Stage I
// Compute rho and rhoB at each local atom site.
// Additionally calculate the D_i values here if we are using the one-site formulation.
// For the two-site formulation we have to calculate the D values in an extra loop (Stage II).
for (ii = iifrom; ii < iito; ii++) {
i = ilist[ii];
xtmp = x[i].x;
ytmp = x[i].y;
ztmp = x[i].z;
itype = type[i];
jlist = firstneigh[i];
jnum = numneigh[i];
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
j &= NEIGHMASK;
delx = xtmp - x[j].x;
dely = ytmp - x[j].y;
delz = ztmp - x[j].z;
rsq = delx*delx + dely*dely + delz*delz;
if(rsq < cutforcesq) {
jtype = type[j];
double r = sqrt(rsq);
const EAMTableIndex index = radiusToTableIndex(r);
double localrho = RhoOfR(index, jtype, itype);
rho_t[i] += localrho;
if(jtype == speciesB) rhoB_t[i] += localrho;
if(NEWTON_PAIR || j < nlocal) {
localrho = RhoOfR(index, itype, jtype);
rho_t[j] += localrho;
if(itype == speciesB) rhoB_t[j] += localrho;
}
if(CDEAMVERSION == 1 && itype != jtype) {
// Note: if the i-j interaction is not concentration dependent (because either
// i or j are not species A or B) then its contribution to D_i and D_j should
// be ignored.
// This if-clause is only required for a ternary.
if((itype == speciesA && jtype == speciesB)
|| (jtype == speciesA && itype == speciesB)) {
double Phi_AB = PhiOfR(index, itype, jtype, 1.0 / r);
D_values_t[i] += Phi_AB;
if(NEWTON_PAIR || j < nlocal)
D_values_t[j] += Phi_AB;
}
}
}
}
}
// wait until all threads are done with computation
sync_threads();
// communicate and sum densities
if (NEWTON_PAIR) {
// reduce per thread density
thr->timer(Timer::PAIR);
data_reduce_thr(rho, nall, nthreads, 1, tid);
data_reduce_thr(rhoB, nall, nthreads, 1, tid);
if (CDEAMVERSION==1)
data_reduce_thr(D_values, nall, nthreads, 1, tid);
// wait until reduction is complete
sync_threads();
#if defined(_OPENMP)
#pragma omp master
#endif
{ communicationStage = 1;
comm->reverse_comm_pair(this); }
// wait until master thread is done with communication
sync_threads();
} else {
// reduce per thread density
thr->timer(Timer::PAIR);
data_reduce_thr(rho, nlocal, nthreads, 1, tid);
data_reduce_thr(rhoB, nlocal, nthreads, 1, tid);
if (CDEAMVERSION==1)
data_reduce_thr(D_values, nlocal, nthreads, 1, tid);
// wait until reduction is complete
sync_threads();
}
// fp = derivative of embedding energy at each atom
// phi = embedding energy at each atom
for (ii = iifrom; ii < iito; ii++) {
i = ilist[ii];
EAMTableIndex index = rhoToTableIndex(rho[i]);
fp[i] = FPrimeOfRho(index, type[i]);
if(EFLAG) {
phi = FofRho(index, type[i]);
e_tally_thr(this, i, i, nlocal, NEWTON_PAIR, phi, 0.0, thr);
}
}
// wait until all theads are done with computation
sync_threads();
// Communicate derivative of embedding function and densities
// and D_values (this for one-site formulation only).
#if defined(_OPENMP)
#pragma omp master
#endif
{ communicationStage = 2;
comm->forward_comm_pair(this); }
// wait until master thread is done with communication
sync_threads();
// The electron densities may not drop to zero because then the concentration would no longer be defined.
// But the concentration is not needed anyway if there is no interaction with another atom, which is the case
// if the electron density is exactly zero. That's why the following lines have been commented out.
//
//for(i = 0; i < nlocal + atom->nghost; i++) {
// if(rho[i] == 0 && (type[i] == speciesA || type[i] == speciesB))
// error->one(FLERR,"CD-EAM potential routine: Detected atom with zero electron density.");
//}
// Stage II
// This is only required for the original two-site formulation of the CD-EAM potential.
if(CDEAMVERSION == 2) {
// Compute intermediate value D_i for each atom.
for (ii = iifrom; ii < iito; ii++) {
i = ilist[ii];
xtmp = x[i].x;
ytmp = x[i].y;
ztmp = x[i].z;
itype = type[i];
jlist = firstneigh[i];
jnum = numneigh[i];
// This code line is required for ternary alloys.
if(itype != speciesA && itype != speciesB) continue;
double x_i = rhoB[i] / rho[i]; // Concentration at atom i.
for(jj = 0; jj < jnum; jj++) {
j = jlist[jj];
j &= NEIGHMASK;
jtype = type[j];
if(itype == jtype) continue;
// This code line is required for ternary alloys.
if(jtype != speciesA && jtype != speciesB) continue;
delx = xtmp - x[j].x;
dely = ytmp - x[j].y;
delz = ztmp - x[j].z;
rsq = delx*delx + dely*dely + delz*delz;
if(rsq < cutforcesq) {
double r = sqrt(rsq);
const EAMTableIndex index = radiusToTableIndex(r);
// The concentration independent part of the cross pair potential.
double Phi_AB = PhiOfR(index, itype, jtype, 1.0 / r);
// Average concentration of two sites
double x_ij = 0.5 * (x_i + rhoB[j]/rho[j]);
// Calculate derivative of h(x_ij) polynomial function.
double h_prime = evalHprime(x_ij);
D_values_t[i] += h_prime * Phi_AB / (2.0 * rho[i] * rho[i]);
if(NEWTON_PAIR || j < nlocal)
D_values_t[j] += h_prime * Phi_AB / (2.0 * rho[j] * rho[j]);
}
}
}
if (NEWTON_PAIR) {
thr->timer(Timer::PAIR);
data_reduce_thr(D_values, nall, nthreads, 1, tid);
// wait until reduction is complete
sync_threads();
#if defined(_OPENMP)
#pragma omp master
#endif
{ communicationStage = 3;
comm->reverse_comm_pair(this); }
// wait until master thread is done with communication
sync_threads();
} else {
thr->timer(Timer::PAIR);
data_reduce_thr(D_values, nlocal, nthreads, 1, tid);
// wait until reduction is complete
sync_threads();
}
#if defined(_OPENMP)
#pragma omp master
#endif
{ communicationStage = 4;
comm->forward_comm_pair(this); }
// wait until master thread is done with communication
sync_threads();
}
// Stage III
// Compute force acting on each atom.
for (ii = iifrom; ii < iito; ii++) {
i = ilist[ii];
xtmp = x[i].x;
ytmp = x[i].y;
ztmp = x[i].z;
itype = type[i];
fxtmp = fytmp = fztmp = 0.0;
jlist = firstneigh[i];
jnum = numneigh[i];
// Concentration at site i
double x_i = -1.0; // The value -1 indicates: no concentration dependence for all interactions of atom i.
// It will be replaced by the concentration at site i if atom i is either A or B.
double D_i, h_prime_i;
// This if-clause is only required for ternary alloys.
if((itype == speciesA || itype == speciesB) && rho[i] != 0.0) {
// Compute local concentration at site i.
x_i = rhoB[i]/rho[i];
ASSERT(x_i >= 0 && x_i<=1.0);
if(CDEAMVERSION == 1) {
// Calculate derivative of h(x_i) polynomial function.
h_prime_i = evalHprime(x_i);
D_i = D_values[i] * h_prime_i / (2.0 * rho[i] * rho[i]);
} else if(CDEAMVERSION == 2) {
D_i = D_values[i];
} else {
ASSERT(false);
}
}
for(jj = 0; jj < jnum; jj++) {
j = jlist[jj];
j &= NEIGHMASK;
delx = xtmp - x[j].x;
dely = ytmp - x[j].y;
delz = ztmp - x[j].z;
rsq = delx*delx + dely*dely + delz*delz;
if(rsq < cutforcesq) {
jtype = type[j];
double r = sqrt(rsq);
const EAMTableIndex index = radiusToTableIndex(r);
// rhoip = derivative of (density at atom j due to atom i)
// rhojp = derivative of (density at atom i due to atom j)
// psip needs both fp[i] and fp[j] terms since r_ij appears in two
// terms of embed eng: Fi(sum rho_ij) and Fj(sum rho_ji)
// hence embed' = Fi(sum rho_ij) rhojp + Fj(sum rho_ji) rhoip
rhoip = RhoPrimeOfR(index, itype, jtype);
rhojp = RhoPrimeOfR(index, jtype, itype);
fpair = fp[i]*rhojp + fp[j]*rhoip;
recip = 1.0/r;
double x_j = -1; // The value -1 indicates: no concentration dependence for this i-j pair
// because atom j is not of species A nor B.
// This code line is required for ternary alloy.
if(jtype == speciesA || jtype == speciesB) {
ASSERT(rho[i] != 0.0);
ASSERT(rho[j] != 0.0);
// Compute local concentration at site j.
x_j = rhoB[j]/rho[j];
ASSERT(x_j >= 0 && x_j<=1.0);
double D_j;
if(CDEAMVERSION == 1) {
// Calculate derivative of h(x_j) polynomial function.
double h_prime_j = evalHprime(x_j);
D_j = D_values[j] * h_prime_j / (2.0 * rho[j] * rho[j]);
} else if(CDEAMVERSION == 2) {
D_j = D_values[j];
} else {
ASSERT(false);
}
double t2 = -rhoB[j];
if(itype == speciesB) t2 += rho[j];
fpair += D_j * rhoip * t2;
}
// This if-clause is only required for a ternary alloy.
// Actually we don't need it at all because D_i should be zero anyway if
// atom i has no concentration dependent interactions (because it is not species A or B).
if(x_i != -1.0) {
double t1 = -rhoB[i];
if(jtype == speciesB) t1 += rho[i];
fpair += D_i * rhojp * t1;
}
double phip;
double phi = PhiOfR(index, itype, jtype, recip, phip);
if(itype == jtype || x_i == -1.0 || x_j == -1.0) {
// Case of no concentration dependence.
fpair += phip;
} else {
// We have a concentration dependence for the i-j interaction.
double h;
if(CDEAMVERSION == 1) {
// Calculate h(x_i) polynomial function.
double h_i = evalH(x_i);
// Calculate h(x_j) polynomial function.
double h_j = evalH(x_j);
h = 0.5 * (h_i + h_j);
} else if(CDEAMVERSION == 2) {
// Average concentration.
double x_ij = 0.5 * (x_i + x_j);
// Calculate h(x_ij) polynomial function.
h = evalH(x_ij);
} else {
ASSERT(false);
}
fpair += h * phip;
phi *= h;
}
// Divide by r_ij and negate to get forces from gradient.
fpair /= -r;
fxtmp += delx*fpair;
fytmp += dely*fpair;
fztmp += delz*fpair;
if(NEWTON_PAIR || j < nlocal) {
f[j].x -= delx*fpair;
f[j].y -= dely*fpair;
f[j].z -= delz*fpair;
}
if(EFLAG) evdwl = phi;
if(EVFLAG) ev_tally_thr(this,i,j,nlocal,NEWTON_PAIR,evdwl,0.0,
fpair,delx,dely,delz,thr);
}
}
f[i].x += fxtmp;
f[i].y += fytmp;
f[i].z += fztmp;
}
}
/* ---------------------------------------------------------------------- */
double PairCDEAMOMP::memory_usage()
{
double bytes = memory_usage_thr();
bytes += PairCDEAM::memory_usage();
return bytes;
}

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