d79be293f5
the special_lj values may be changed for individual hybrid sub-styles with pair_modify pair special. thus the factor_sqrt[] array may have incorrect values when computed during Pair::init_style().
273 lines
8.2 KiB
C++
273 lines
8.2 KiB
C++
// clang-format off
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/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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https://www.lammps.org/, Sandia National Laboratories
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LAMMPS development team: developers@lammps.org
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This software is distributed under the GNU General Public License.
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See the README file in the top-level LAMMPS directory.
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------------------------------------------------------------------------- */
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/* ----------------------------------------------------------------------
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Contributing author: Axel Kohlmeyer (Temple U)
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------------------------------------------------------------------------- */
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#include "pair_dpd_ext_tstat_omp.h"
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#include "atom.h"
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#include "comm.h"
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#include "force.h"
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#include "neigh_list.h"
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#include "update.h"
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#include "random_mars.h"
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#include "suffix.h"
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#include <cmath>
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#include "omp_compat.h"
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using namespace LAMMPS_NS;
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static constexpr double EPSILON = 1.0e-10;
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/* ---------------------------------------------------------------------- */
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PairDPDExtTstatOMP::PairDPDExtTstatOMP(LAMMPS *lmp) :
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PairDPDExtTstat(lmp), ThrOMP(lmp, THR_PAIR)
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{
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suffix_flag |= Suffix::OMP;
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respa_enable = 0;
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random_thr = nullptr;
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nthreads = 0;
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}
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/* ---------------------------------------------------------------------- */
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PairDPDExtTstatOMP::~PairDPDExtTstatOMP()
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{
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if (random_thr) {
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for (int i=1; i < nthreads; ++i)
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delete random_thr[i];
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delete[] random_thr;
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random_thr = nullptr;
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}
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}
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/* ---------------------------------------------------------------------- */
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void PairDPDExtTstatOMP::compute(int eflag, int vflag)
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{
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ev_init(eflag,vflag);
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// precompute random force scaling factors
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for (int i = 0; i < 4; ++i) special_sqrt[i] = sqrt(force->special_lj[i]);
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const int nall = atom->nlocal + atom->nghost;
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const int inum = list->inum;
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// number of threads has changed. reallocate pool of pRNGs
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if (nthreads != comm->nthreads) {
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if (random_thr) {
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for (int i=1; i < nthreads; ++i)
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delete random_thr[i];
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delete[] random_thr;
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}
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nthreads = comm->nthreads;
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random_thr = new RanMars*[nthreads];
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for (int i=1; i < nthreads; ++i)
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random_thr[i] = nullptr;
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// to ensure full compatibility with the serial DPD style
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// we use the serial random number generator instance for thread 0
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random_thr[0] = random;
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}
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// adjust sigma if target T is changing
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if (t_start != t_stop) {
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double delta = update->ntimestep - update->beginstep;
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if (delta != 0.0) delta /= update->endstep - update->beginstep;
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temperature = t_start + delta * (t_stop-t_start);
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double boltz = force->boltz;
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for (int i = 1; i <= atom->ntypes; i++) {
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for (int j = i; j <= atom->ntypes; j++) {
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sigma[i][j] = sigma[j][i] = sqrt(2.0*boltz*temperature*gamma[i][j]);
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sigmaT[i][j] = sigmaT[j][i] = sqrt(2.0*boltz*temperature*gammaT[i][j]);
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}
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}
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}
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#if defined(_OPENMP)
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#pragma omp parallel LMP_DEFAULT_NONE LMP_SHARED(eflag,vflag)
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#endif
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{
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int ifrom, ito, tid;
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loop_setup_thr(ifrom, ito, tid, inum, nthreads);
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ThrData *thr = fix->get_thr(tid);
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thr->timer(Timer::START);
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ev_setup_thr(eflag, vflag, nall, eatom, vatom, nullptr, thr);
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// generate a random number generator instance for
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// all threads != 0. make sure we use unique seeds.
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if ((tid > 0) && (random_thr[tid] == nullptr))
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random_thr[tid] = new RanMars(Pair::lmp, seed + comm->me
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+ comm->nprocs*tid);
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if (evflag) {
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if (eflag) {
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if (force->newton_pair) eval<1,1,1>(ifrom, ito, thr);
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else eval<1,1,0>(ifrom, ito, thr);
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} else {
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if (force->newton_pair) eval<1,0,1>(ifrom, ito, thr);
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else eval<1,0,0>(ifrom, ito, thr);
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}
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} else {
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if (force->newton_pair) eval<0,0,1>(ifrom, ito, thr);
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else eval<0,0,0>(ifrom, ito, thr);
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}
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thr->timer(Timer::PAIR);
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reduce_thr(this, eflag, vflag, thr);
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} // end of omp parallel region
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}
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template <int EVFLAG, int EFLAG, int NEWTON_PAIR>
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void PairDPDExtTstatOMP::eval(int iifrom, int iito, ThrData * const thr)
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{
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int i,j,ii,jj,jnum,itype,jtype;
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double xtmp,ytmp,ztmp,delx,dely,delz,fpairx,fpairy,fpairz,fpair;
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double vxtmp,vytmp,vztmp,delvx,delvy,delvz;
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double rsq,r,rinv,dot,wd,wdPar,wdPerp,randnum,randnumx,randnumy,randnumz,factor_dpd,factor_sqrt;
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double P[3][3];
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int *ilist,*jlist,*numneigh,**firstneigh;
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const auto * _noalias const x = (dbl3_t *) atom->x[0];
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const auto * _noalias const v = (dbl3_t *) atom->v[0];
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auto * _noalias const f = (dbl3_t *) thr->get_f()[0];
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const int * _noalias const type = atom->type;
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const int nlocal = atom->nlocal;
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const double *special_lj = force->special_lj;
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const double dtinvsqrt = 1.0/sqrt(update->dt);
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double fxtmp,fytmp,fztmp;
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RanMars &rng = *random_thr[thr->get_tid()];
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ilist = list->ilist;
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numneigh = list->numneigh;
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firstneigh = list->firstneigh;
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// loop over neighbors of my atoms
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for (ii = iifrom; ii < iito; ++ii) {
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i = ilist[ii];
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xtmp = x[i].x;
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ytmp = x[i].y;
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ztmp = x[i].z;
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vxtmp = v[i].x;
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vytmp = v[i].y;
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vztmp = v[i].z;
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itype = type[i];
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jlist = firstneigh[i];
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jnum = numneigh[i];
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fxtmp=fytmp=fztmp=0.0;
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for (jj = 0; jj < jnum; jj++) {
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j = jlist[jj];
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factor_dpd = special_lj[sbmask(j)];
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factor_sqrt = special_sqrt[sbmask(j)];
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j &= NEIGHMASK;
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delx = xtmp - x[j].x;
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dely = ytmp - x[j].y;
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delz = ztmp - x[j].z;
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rsq = delx*delx + dely*dely + delz*delz;
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jtype = type[j];
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if (rsq < cutsq[itype][jtype]) {
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r = sqrt(rsq);
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if (r < EPSILON) continue; // r can be 0.0 in DPD systems
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rinv = 1.0/r;
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delvx = vxtmp - v[j].x;
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delvy = vytmp - v[j].y;
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delvz = vztmp - v[j].z;
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dot = delx*delvx + dely*delvy + delz*delvz;
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P[0][0] = 1.0 - delx*delx*rinv*rinv;
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P[0][1] = - delx*dely*rinv*rinv;
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P[0][2] = - delx*delz*rinv*rinv;
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P[1][0] = P[0][1];
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P[1][1] = 1.0 - dely*dely*rinv*rinv;
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P[1][2] = - dely*delz*rinv*rinv;
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P[2][0] = P[0][2];
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P[2][1] = P[1][2];
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P[2][2] = 1.0 - delz*delz*rinv*rinv;
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wd = 1.0 - r/cut[itype][jtype];
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wdPar = pow(wd,ws[itype][jtype]);
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wdPerp = pow(wd,wsT[itype][jtype]);
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randnum = rng.gaussian();
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randnumx = rng.gaussian();
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randnumy = rng.gaussian();
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randnumz = rng.gaussian();
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// drag force - parallel
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fpair = -factor_dpd*gamma[itype][jtype]*wdPar*wdPar*dot*rinv;
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// random force - parallel
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fpair += factor_sqrt*sigma[itype][jtype]*wdPar*randnum*dtinvsqrt;
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fpairx = fpair*rinv*delx;
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fpairy = fpair*rinv*dely;
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fpairz = fpair*rinv*delz;
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// drag force - perpendicular
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const double prefactor_g = factor_dpd * gammaT[itype][jtype]*wdPerp*wdPerp;
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fpairx -= prefactor_g * (P[0][0]*delvx + P[0][1]*delvy + P[0][2]*delvz);
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fpairy -= prefactor_g * (P[1][0]*delvx + P[1][1]*delvy + P[1][2]*delvz);
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fpairz -= prefactor_g * (P[2][0]*delvx + P[2][1]*delvy + P[2][2]*delvz);
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// random force - perpendicular
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const double prefactor_s = factor_sqrt * sigmaT[itype][jtype]*wdPerp * dtinvsqrt;
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fpairx += prefactor_s * (P[0][0]*randnumx + P[0][1]*randnumy + P[0][2]*randnumz);
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fpairy += prefactor_s * (P[1][0]*randnumx + P[1][1]*randnumy + P[1][2]*randnumz);
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fpairz += prefactor_s * (P[2][0]*randnumx + P[2][1]*randnumy + P[2][2]*randnumz);
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fxtmp += fpairx;
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fytmp += fpairy;
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fztmp += fpairz;
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if (NEWTON_PAIR || j < nlocal) {
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f[j].x -= fpairx;
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f[j].y -= fpairy;
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f[j].z -= fpairz;
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}
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if (EVFLAG) ev_tally_xyz_thr(this, i,j,nlocal,NEWTON_PAIR,0.0,0.0,
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fpairx,fpairy,fpairz,delx,dely,delz,thr);
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}
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}
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f[i].x += fxtmp;
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f[i].y += fytmp;
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f[i].z += fztmp;
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}
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}
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/* ---------------------------------------------------------------------- */
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double PairDPDExtTstatOMP::memory_usage()
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{
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double bytes = memory_usage_thr();
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bytes += PairDPDExtTstat::memory_usage();
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bytes += (double)comm->nthreads * sizeof(RanMars*);
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bytes += (double)comm->nthreads * sizeof(RanMars);
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return bytes;
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}
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