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lammps/src/GPU/pair_lj_cut_dipole_cut_gpu.cpp
Axel Kohlmeyer 2132b1d904 update developer reference text
2022-10-24 11:08:26 -04:00

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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
https://www.lammps.org/, Sandia National Laboratories
LAMMPS development team: developers@lammps.org
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: Trung Dac Nguyen (ORNL)
------------------------------------------------------------------------- */
#include "pair_lj_cut_dipole_cut_gpu.h"
#include "atom.h"
#include "domain.h"
#include "error.h"
#include "force.h"
#include "gpu_extra.h"
#include "neigh_list.h"
#include "neighbor.h"
#include "suffix.h"
#include "update.h"
#include <cmath>
#include <cstring>
using namespace LAMMPS_NS;
// External functions from cuda library for atom decomposition
int dpl_gpu_init(const int ntypes, double **cutsq, double **host_lj1, double **host_lj2,
double **host_lj3, double **host_lj4, double **offset, double *special_lj,
const int nlocal, const int nall, const int max_nbors, const int maxspecial,
const double cell_size, int &gpu_mode, FILE *screen, double **host_cut_ljsq,
double **host_cut_coulsq, double *host_special_coul, const double qqrd2e);
void dpl_gpu_clear();
int **dpl_gpu_compute_n(const int ago, const int inum, const int nall, double **host_x,
int *host_type, double *sublo, double *subhi, tagint *tag, int **nspecial,
tagint **special, const bool eflag, const bool vflag, const bool eatom,
const bool vatom, int &host_start, int **ilist, int **jnum,
const double cpu_time, bool &success, double *host_q, double **host_mu,
double *boxlo, double *prd);
void dpl_gpu_compute(const int ago, const int inum, const int nall, double **host_x, int *host_type,
int *ilist, int *numj, int **firstneigh, const bool eflag, const bool vflag,
const bool eatom, const bool vatom, int &host_start, const double cpu_time,
bool &success, double *host_q, double **host_mu, const int nlocal,
double *boxlo, double *prd);
double dpl_gpu_bytes();
/* ---------------------------------------------------------------------- */
PairLJCutDipoleCutGPU::PairLJCutDipoleCutGPU(LAMMPS *lmp) :
PairLJCutDipoleCut(lmp), gpu_mode(GPU_FORCE)
{
respa_enable = 0;
reinitflag = 0;
cpu_time = 0.0;
suffix_flag |= Suffix::GPU;
GPU_EXTRA::gpu_ready(lmp->modify, lmp->error);
}
/* ----------------------------------------------------------------------
free all arrays
------------------------------------------------------------------------- */
PairLJCutDipoleCutGPU::~PairLJCutDipoleCutGPU()
{
dpl_gpu_clear();
}
/* ---------------------------------------------------------------------- */
void PairLJCutDipoleCutGPU::compute(int eflag, int vflag)
{
ev_init(eflag, vflag);
int nall = atom->nlocal + atom->nghost;
int inum, host_start;
bool success = true;
int *ilist, *numneigh, **firstneigh;
if (gpu_mode != GPU_FORCE) {
double sublo[3], subhi[3];
if (domain->triclinic == 0) {
sublo[0] = domain->sublo[0];
sublo[1] = domain->sublo[1];
sublo[2] = domain->sublo[2];
subhi[0] = domain->subhi[0];
subhi[1] = domain->subhi[1];
subhi[2] = domain->subhi[2];
} else {
domain->bbox(domain->sublo_lamda, domain->subhi_lamda, sublo, subhi);
}
inum = atom->nlocal;
firstneigh = dpl_gpu_compute_n(neighbor->ago, inum, nall, atom->x, atom->type, sublo, subhi,
atom->tag, atom->nspecial, atom->special, eflag, vflag,
eflag_atom, vflag_atom, host_start, &ilist, &numneigh, cpu_time,
success, atom->q, atom->mu, domain->boxlo, domain->prd);
} else {
inum = list->inum;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
dpl_gpu_compute(neighbor->ago, inum, nall, atom->x, atom->type, ilist, numneigh, firstneigh,
eflag, vflag, eflag_atom, vflag_atom, host_start, cpu_time, success, atom->q,
atom->mu, atom->nlocal, domain->boxlo, domain->prd);
}
if (!success) error->one(FLERR, "Insufficient memory on accelerator");
if (host_start < inum) {
cpu_time = platform::walltime();
cpu_compute(host_start, inum, eflag, vflag, ilist, numneigh, firstneigh);
cpu_time = platform::walltime() - cpu_time;
}
}
/* ----------------------------------------------------------------------
init specific to this pair style
------------------------------------------------------------------------- */
void PairLJCutDipoleCutGPU::init_style()
{
if (!atom->q_flag || !atom->mu_flag || !atom->torque_flag)
error->all(FLERR, "Pair dipole/cut/gpu requires atom attributes q, mu, torque");
if (strcmp(update->unit_style, "electron") == 0)
error->all(FLERR, "Cannot (yet) use 'electron' units with dipoles");
// Repeat cutsq calculation because done after call to init_style
double maxcut = -1.0;
double cut;
for (int i = 1; i <= atom->ntypes; i++) {
for (int j = i; j <= atom->ntypes; j++) {
if (setflag[i][j] != 0 || (setflag[i][i] != 0 && setflag[j][j] != 0)) {
cut = init_one(i, j);
cut *= cut;
if (cut > maxcut) maxcut = cut;
cutsq[i][j] = cutsq[j][i] = cut;
} else
cutsq[i][j] = cutsq[j][i] = 0.0;
}
}
double cell_size = sqrt(maxcut) + neighbor->skin;
int maxspecial = 0;
if (atom->molecular != Atom::ATOMIC) maxspecial = atom->maxspecial;
int mnf = 5e-2 * neighbor->oneatom;
int success =
dpl_gpu_init(atom->ntypes + 1, cutsq, lj1, lj2, lj3, lj4, offset, force->special_lj,
atom->nlocal, atom->nlocal + atom->nghost, mnf, maxspecial, cell_size, gpu_mode,
screen, cut_ljsq, cut_coulsq, force->special_coul, force->qqrd2e);
GPU_EXTRA::check_flag(success, error, world);
if (gpu_mode == GPU_FORCE) neighbor->add_request(this, NeighConst::REQ_FULL);
}
/* ---------------------------------------------------------------------- */
double PairLJCutDipoleCutGPU::memory_usage()
{
double bytes = Pair::memory_usage();
return bytes + dpl_gpu_bytes();
}
/* ---------------------------------------------------------------------- */
void PairLJCutDipoleCutGPU::cpu_compute(int start, int inum, int eflag, int vflag, int *ilist,
int *numneigh, int **firstneigh)
{
int i, j, ii, jj, jnum, itype, jtype;
double qtmp, xtmp, ytmp, ztmp, delx, dely, delz, evdwl, ecoul, fx, fy, fz;
double rsq, rinv, r2inv, r6inv, r3inv, r5inv, r7inv;
double forcecoulx, forcecouly, forcecoulz, crossx, crossy, crossz;
double tixcoul, tiycoul, tizcoul, tjxcoul, tjycoul, tjzcoul;
double fq, pdotp, pidotr, pjdotr, pre1, pre2, pre3, pre4;
double forcelj, factor_coul, factor_lj;
int *jlist;
evdwl = ecoul = 0.0;
ev_init(eflag, vflag);
double **x = atom->x;
double **f = atom->f;
double *q = atom->q;
double **mu = atom->mu;
double **torque = atom->torque;
int *type = atom->type;
double *special_coul = force->special_coul;
double *special_lj = force->special_lj;
double qqrd2e = force->qqrd2e;
// loop over neighbors of my atoms
for (ii = start; 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;
rinv = sqrt(r2inv);
// atom can have both a charge and dipole
// i,j = charge-charge, dipole-dipole, dipole-charge, or charge-dipole
forcecoulx = forcecouly = forcecoulz = 0.0;
tixcoul = tiycoul = tizcoul = 0.0;
tjxcoul = tjycoul = tjzcoul = 0.0;
if (rsq < cut_coulsq[itype][jtype]) {
if (qtmp != 0.0 && q[j] != 0.0) {
r3inv = r2inv * rinv;
pre1 = qtmp * q[j] * r3inv;
forcecoulx += pre1 * delx;
forcecouly += pre1 * dely;
forcecoulz += pre1 * delz;
}
if (mu[i][3] > 0.0 && mu[j][3] > 0.0) {
r3inv = r2inv * rinv;
r5inv = r3inv * r2inv;
r7inv = r5inv * r2inv;
pdotp = mu[i][0] * mu[j][0] + mu[i][1] * mu[j][1] + mu[i][2] * mu[j][2];
pidotr = mu[i][0] * delx + mu[i][1] * dely + mu[i][2] * delz;
pjdotr = mu[j][0] * delx + mu[j][1] * dely + mu[j][2] * delz;
pre1 = 3.0 * r5inv * pdotp - 15.0 * r7inv * pidotr * pjdotr;
pre2 = 3.0 * r5inv * pjdotr;
pre3 = 3.0 * r5inv * pidotr;
pre4 = -1.0 * r3inv;
forcecoulx += pre1 * delx + pre2 * mu[i][0] + pre3 * mu[j][0];
forcecouly += pre1 * dely + pre2 * mu[i][1] + pre3 * mu[j][1];
forcecoulz += pre1 * delz + pre2 * mu[i][2] + pre3 * mu[j][2];
crossx = pre4 * (mu[i][1] * mu[j][2] - mu[i][2] * mu[j][1]);
crossy = pre4 * (mu[i][2] * mu[j][0] - mu[i][0] * mu[j][2]);
crossz = pre4 * (mu[i][0] * mu[j][1] - mu[i][1] * mu[j][0]);
tixcoul += crossx + pre2 * (mu[i][1] * delz - mu[i][2] * dely);
tiycoul += crossy + pre2 * (mu[i][2] * delx - mu[i][0] * delz);
tizcoul += crossz + pre2 * (mu[i][0] * dely - mu[i][1] * delx);
tjxcoul += -crossx + pre3 * (mu[j][1] * delz - mu[j][2] * dely);
tjycoul += -crossy + pre3 * (mu[j][2] * delx - mu[j][0] * delz);
tjzcoul += -crossz + pre3 * (mu[j][0] * dely - mu[j][1] * delx);
}
if (mu[i][3] > 0.0 && q[j] != 0.0) {
r3inv = r2inv * rinv;
r5inv = r3inv * r2inv;
pidotr = mu[i][0] * delx + mu[i][1] * dely + mu[i][2] * delz;
pre1 = 3.0 * q[j] * r5inv * pidotr;
pre2 = q[j] * r3inv;
forcecoulx += pre2 * mu[i][0] - pre1 * delx;
forcecouly += pre2 * mu[i][1] - pre1 * dely;
forcecoulz += pre2 * mu[i][2] - pre1 * delz;
tixcoul += pre2 * (mu[i][1] * delz - mu[i][2] * dely);
tiycoul += pre2 * (mu[i][2] * delx - mu[i][0] * delz);
tizcoul += pre2 * (mu[i][0] * dely - mu[i][1] * delx);
}
if (mu[j][3] > 0.0 && qtmp != 0.0) {
r3inv = r2inv * rinv;
r5inv = r3inv * r2inv;
pjdotr = mu[j][0] * delx + mu[j][1] * dely + mu[j][2] * delz;
pre1 = 3.0 * qtmp * r5inv * pjdotr;
pre2 = qtmp * r3inv;
forcecoulx += pre1 * delx - pre2 * mu[j][0];
forcecouly += pre1 * dely - pre2 * mu[j][1];
forcecoulz += pre1 * delz - pre2 * mu[j][2];
tjxcoul += -pre2 * (mu[j][1] * delz - mu[j][2] * dely);
tjycoul += -pre2 * (mu[j][2] * delx - mu[j][0] * delz);
tjzcoul += -pre2 * (mu[j][0] * dely - mu[j][1] * delx);
}
}
// LJ interaction
if (rsq < cut_ljsq[itype][jtype]) {
r6inv = r2inv * r2inv * r2inv;
forcelj = r6inv * (lj1[itype][jtype] * r6inv - lj2[itype][jtype]);
forcelj *= factor_lj * r2inv;
} else
forcelj = 0.0;
// total force
fq = factor_coul * qqrd2e;
fx = fq * forcecoulx + delx * forcelj;
fy = fq * forcecouly + dely * forcelj;
fz = fq * forcecoulz + delz * forcelj;
// force & torque accumulation
f[i][0] += fx;
f[i][1] += fy;
f[i][2] += fz;
torque[i][0] += fq * tixcoul;
torque[i][1] += fq * tiycoul;
torque[i][2] += fq * tizcoul;
if (eflag) {
if (rsq < cut_coulsq[itype][jtype]) {
ecoul = qtmp * q[j] * rinv;
if (mu[i][3] > 0.0 && mu[j][3] > 0.0)
ecoul += r3inv * pdotp - 3.0 * r5inv * pidotr * pjdotr;
if (mu[i][3] > 0.0 && q[j] != 0.0) ecoul += -q[j] * r3inv * pidotr;
if (mu[j][3] > 0.0 && qtmp != 0.0) ecoul += qtmp * r3inv * pjdotr;
ecoul *= factor_coul * qqrd2e;
} else
ecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
evdwl = r6inv * (lj3[itype][jtype] * r6inv - lj4[itype][jtype]) - offset[itype][jtype];
evdwl *= factor_lj;
} else
evdwl = 0.0;
}
if (evflag) ev_tally_xyz_full(i, evdwl, ecoul, fx, fy, fz, delx, dely, delz);
}
}
}
}
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