284 lines
9.4 KiB
C++
284 lines
9.4 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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https://lammps.sandia.gov/, Sandia National Laboratories
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Steve Plimpton, sjplimp@sandia.gov
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Copyright (2003) Sandia Corporation. Under the terms of Contract
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DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
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certain rights in this software. This software is distributed under
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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: Trung Dac Nguyen (ORNL)
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------------------------------------------------------------------------- */
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#include "pair_coul_dsf_gpu.h"
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#include <cmath>
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#include <cstdio>
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#include <cstring>
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#include "atom.h"
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#include "atom_vec.h"
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#include "comm.h"
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#include "force.h"
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#include "neighbor.h"
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#include "neigh_list.h"
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#include "integrate.h"
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#include "memory.h"
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#include "error.h"
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#include "neigh_request.h"
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#include "universe.h"
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#include "update.h"
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#include "domain.h"
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#include "gpu_extra.h"
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#include "suffix.h"
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#define MY_PIS 1.77245385090551602729
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#define EWALD_F 1.12837917
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#define EWALD_P 0.3275911
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#define A1 0.254829592
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#define A2 -0.284496736
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#define A3 1.421413741
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#define A4 -1.453152027
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#define A5 1.061405429
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using namespace LAMMPS_NS;
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// External functions from cuda library for atom decomposition
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int cdsf_gpu_init(const int ntypes, const int nlocal, const int nall,
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const int max_nbors, const int maxspecial,
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const double cell_size, int &gpu_mode, FILE *screen,
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const double host_cut_coulsq,
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double *host_special_coul, const double qqrd2e,
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const double e_shift, const double f_shift,
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const double alpha);
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void cdsf_gpu_clear();
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int ** cdsf_gpu_compute_n(const int ago, const int inum,
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const int nall, double **host_x, int *host_type,
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double *sublo, double *subhi, tagint *tag, int **nspecial,
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tagint **special, const bool eflag, const bool vflag,
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const bool eatom, const bool vatom, int &host_start,
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int **ilist, int **jnum, const double cpu_time,
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bool &success, double *host_q, double *boxlo,
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double *prd);
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void cdsf_gpu_compute(const int ago, const int inum,
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const int nall, double **host_x, int *host_type,
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int *ilist, int *numj, int **firstneigh,
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const bool eflag, const bool vflag, const bool eatom,
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const bool vatom, int &host_start, const double cpu_time,
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bool &success, double *host_q, const int nlocal,
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double *boxlo, double *prd);
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double cdsf_gpu_bytes();
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/* ---------------------------------------------------------------------- */
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PairCoulDSFGPU::PairCoulDSFGPU(LAMMPS *lmp) : PairCoulDSF(lmp),
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gpu_mode(GPU_FORCE)
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{
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respa_enable = 0;
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reinitflag = 0;
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cpu_time = 0.0;
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suffix_flag |= Suffix::GPU;
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GPU_EXTRA::gpu_ready(lmp->modify, lmp->error);
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}
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/* ----------------------------------------------------------------------
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free all arrays
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------------------------------------------------------------------------- */
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PairCoulDSFGPU::~PairCoulDSFGPU()
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{
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cdsf_gpu_clear();
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}
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/* ---------------------------------------------------------------------- */
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void PairCoulDSFGPU::compute(int eflag, int vflag)
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{
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ev_init(eflag,vflag);
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int nall = atom->nlocal + atom->nghost;
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int inum, host_start;
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bool success = true;
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int *ilist, *numneigh, **firstneigh;
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if (gpu_mode != GPU_FORCE) {
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double sublo[3],subhi[3];
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if (domain->triclinic == 0) {
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sublo[0] = domain->sublo[0];
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sublo[1] = domain->sublo[1];
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sublo[2] = domain->sublo[2];
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subhi[0] = domain->subhi[0];
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subhi[1] = domain->subhi[1];
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subhi[2] = domain->subhi[2];
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} else {
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domain->bbox(domain->sublo_lamda,domain->subhi_lamda,sublo,subhi);
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}
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inum = atom->nlocal;
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firstneigh = cdsf_gpu_compute_n(neighbor->ago, inum, nall, atom->x,
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atom->type, sublo, subhi,
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atom->tag, atom->nspecial, atom->special,
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eflag, vflag, eflag_atom, vflag_atom,
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host_start, &ilist, &numneigh, cpu_time,
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success, atom->q, domain->boxlo,
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domain->prd);
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} else {
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inum = list->inum;
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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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cdsf_gpu_compute(neighbor->ago, inum, nall, atom->x, atom->type,
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ilist, numneigh, firstneigh, eflag, vflag, eflag_atom,
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vflag_atom, host_start, cpu_time, success, atom->q,
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atom->nlocal, domain->boxlo, domain->prd);
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}
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if (!success)
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error->one(FLERR,"Insufficient memory on accelerator");
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if (host_start<inum) {
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cpu_time = MPI_Wtime();
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cpu_compute(host_start, inum, eflag, vflag, ilist, numneigh, firstneigh);
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cpu_time = MPI_Wtime() - cpu_time;
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}
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}
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/* ----------------------------------------------------------------------
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init specific to this pair style
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------------------------------------------------------------------------- */
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void PairCoulDSFGPU::init_style()
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{
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if (!atom->q_flag)
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error->all(FLERR,"Pair style coul/dsf/gpu requires atom attribute q");
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if (force->newton_pair)
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error->all(FLERR,"Cannot use newton pair with coul/dsf/gpu pair style");
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// Repeat cutsq calculation because done after call to init_style
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double maxcut = -1.0;
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double cut;
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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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if (setflag[i][j] != 0 || (setflag[i][i] != 0 && setflag[j][j] != 0)) {
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cut = init_one(i,j);
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cut *= cut;
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if (cut > maxcut)
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maxcut = cut;
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cutsq[i][j] = cutsq[j][i] = cut;
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} else
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cutsq[i][j] = cutsq[j][i] = 0.0;
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}
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}
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double cell_size = sqrt(maxcut) + neighbor->skin;
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cut_coulsq = cut_coul * cut_coul;
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double erfcc = erfc(alpha*cut_coul);
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double erfcd = exp(-alpha*alpha*cut_coul*cut_coul);
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f_shift = -(erfcc/cut_coulsq + 2.0/MY_PIS*alpha*erfcd/cut_coul);
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e_shift = erfcc/cut_coul - f_shift*cut_coul;
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int maxspecial=0;
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if (atom->molecular)
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maxspecial=atom->maxspecial;
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int success = cdsf_gpu_init(atom->ntypes+1, atom->nlocal,
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atom->nlocal+atom->nghost, 300, maxspecial,
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cell_size, gpu_mode, screen, cut_coulsq,
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force->special_coul, force->qqrd2e, e_shift,
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f_shift, alpha);
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GPU_EXTRA::check_flag(success,error,world);
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if (gpu_mode == GPU_FORCE) {
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int irequest = neighbor->request(this,instance_me);
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neighbor->requests[irequest]->half = 0;
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neighbor->requests[irequest]->full = 1;
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}
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}
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/* ---------------------------------------------------------------------- */
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double PairCoulDSFGPU::memory_usage()
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{
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double bytes = Pair::memory_usage();
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return bytes + cdsf_gpu_bytes();
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}
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/* ---------------------------------------------------------------------- */
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void PairCoulDSFGPU::cpu_compute(int start, int inum, int eflag,
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int /* vflag */, int *ilist,
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int *numneigh, int **firstneigh)
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{
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int i,j,ii,jj,jnum;
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double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,ecoul,fpair;
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double r,rsq,r2inv,forcecoul,factor_coul;
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double prefactor,erfcc,erfcd,t;
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int *jlist;
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ecoul = 0.0;
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double **x = atom->x;
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double **f = atom->f;
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double *q = atom->q;
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int nlocal = atom->nlocal;
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double *special_coul = force->special_coul;
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double qqrd2e = force->qqrd2e;
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// loop over neighbors of my atoms
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for (ii = start; ii < inum; ii++) {
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i = ilist[ii];
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qtmp = q[i];
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xtmp = x[i][0];
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ytmp = x[i][1];
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ztmp = x[i][2];
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jlist = firstneigh[i];
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jnum = numneigh[i];
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if (evflag) {
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double e_self = -(e_shift/2.0 + alpha/MY_PIS) * qtmp*qtmp*qqrd2e;
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ev_tally(i,i,nlocal,0,0.0,e_self,0.0,0.0,0.0,0.0);
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}
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for (jj = 0; jj < jnum; jj++) {
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j = jlist[jj];
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factor_coul = special_coul[sbmask(j)];
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j &= NEIGHMASK;
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delx = xtmp - x[j][0];
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dely = ytmp - x[j][1];
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delz = ztmp - x[j][2];
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rsq = delx*delx + dely*dely + delz*delz;
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if (rsq < cut_coulsq) {
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r2inv = 1.0/rsq;
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r = sqrt(rsq);
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prefactor = qqrd2e*qtmp*q[j]/r;
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erfcd = exp(-alpha*alpha*r*r);
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t = 1.0 / (1.0 + EWALD_P*alpha*r);
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erfcc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * erfcd;
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forcecoul = prefactor * (erfcc/r + 2.0*alpha/MY_PIS * erfcd +
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r*f_shift) * r;
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if (factor_coul < 1.0) forcecoul -= (1.0-factor_coul)*prefactor;
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fpair = forcecoul * r2inv;
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f[i][0] += delx*fpair;
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f[i][1] += dely*fpair;
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f[i][2] += delz*fpair;
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if (eflag) {
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if (rsq < cut_coulsq) {
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ecoul = prefactor * (erfcc - r*e_shift - rsq*f_shift);
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if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
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} else ecoul = 0.0;
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}
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if (evflag) ev_tally_full(i,0.0,ecoul,fpair,delx,dely,delz);
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}
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}
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}
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}
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