278 lines
9.4 KiB
C++
278 lines
9.4 KiB
C++
/* ----------------------------------------------------------------------
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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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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: Axel Kohlmeyer (Temple)
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------------------------------------------------------------------------- */
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#include "pair_coul_long_gpu.h"
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#include "atom.h"
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#include "domain.h"
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#include "error.h"
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#include "force.h"
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#include "gpu_extra.h"
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#include "kspace.h"
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#include "neigh_list.h"
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#include "neighbor.h"
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#include "suffix.h"
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#include <cmath>
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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 cl_gpu_init(const int ntypes, double **scale, const int nlocal, const int nall,
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const int max_nbors, const int maxspecial, const double cell_size, int &gpu_mode,
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FILE *screen, double host_cut_coulsq, double *host_special_coul,
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const double qqrd2e, const double g_ewald);
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void cl_gpu_reinit(const int ntypes, double **scale);
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void cl_gpu_clear();
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int **cl_gpu_compute_n(const int ago, const int inum, const int nall, double **host_x,
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int *host_type, double *sublo, double *subhi, tagint *tag, int **nspecial,
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tagint **special, const bool eflag, const bool vflag, const bool eatom,
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const bool vatom, int &host_start, int **ilist, int **jnum,
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const double cpu_time, bool &success, double *host_q, double *boxlo,
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double *prd);
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void cl_gpu_compute(const int ago, const int inum, const int nall, double **host_x, int *host_type,
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int *ilist, int *numj, int **firstneigh, const bool eflag, const bool vflag,
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const bool eatom, const bool vatom, int &host_start, const double cpu_time,
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bool &success, double *host_q, const int nlocal, double *boxlo, double *prd);
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double cl_gpu_bytes();
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/* ---------------------------------------------------------------------- */
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PairCoulLongGPU::PairCoulLongGPU(LAMMPS *lmp) : PairCoulLong(lmp), gpu_mode(GPU_FORCE)
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{
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respa_enable = 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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PairCoulLongGPU::~PairCoulLongGPU()
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{
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cl_gpu_clear();
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}
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/* ---------------------------------------------------------------------- */
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void PairCoulLongGPU::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 = cl_gpu_compute_n(neighbor->ago, inum, nall, atom->x, atom->type, sublo, subhi,
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atom->tag, atom->nspecial, atom->special, eflag, vflag,
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eflag_atom, vflag_atom, host_start, &ilist, &numneigh, cpu_time,
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success, atom->q, domain->boxlo, 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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cl_gpu_compute(neighbor->ago, inum, nall, atom->x, atom->type, ilist, numneigh, firstneigh,
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eflag, vflag, eflag_atom, 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) error->one(FLERR, "Insufficient memory on accelerator");
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if (host_start < inum) {
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cpu_time = platform::walltime();
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cpu_compute(host_start, inum, eflag, vflag, ilist, numneigh, firstneigh);
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cpu_time = platform::walltime() - 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 PairCoulLongGPU::init_style()
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{
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cut_respa = nullptr;
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if (!atom->q_flag) error->all(FLERR, "Pair style coul/long/gpu requires atom attribute q");
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// Call init_one calculation make sure scale is correct
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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)) { init_one(i, j); }
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}
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}
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double cell_size = cut_coul + neighbor->skin;
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cut_coulsq = cut_coul * cut_coul;
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// insure use of KSpace long-range solver, set g_ewald
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if (force->kspace == nullptr) error->all(FLERR, "Pair style requires a KSpace style");
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g_ewald = force->kspace->g_ewald;
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// setup force tables
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if (ncoultablebits) init_tables(cut_coul, cut_respa);
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int maxspecial = 0;
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if (atom->molecular != Atom::ATOMIC) maxspecial = atom->maxspecial;
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int mnf = 5e-2 * neighbor->oneatom;
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int success = cl_gpu_init(atom->ntypes + 1, scale, atom->nlocal, atom->nlocal + atom->nghost, mnf,
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maxspecial, cell_size, gpu_mode, screen, cut_coulsq,
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force->special_coul, force->qqrd2e, g_ewald);
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GPU_EXTRA::check_flag(success, error, world);
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if (gpu_mode == GPU_FORCE) neighbor->add_request(this, NeighConst::REQ_FULL);
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}
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/* ---------------------------------------------------------------------- */
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void PairCoulLongGPU::reinit()
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{
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Pair::reinit();
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cl_gpu_reinit(atom->ntypes + 1, scale);
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}
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/* ---------------------------------------------------------------------- */
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double PairCoulLongGPU::memory_usage()
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{
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double bytes = Pair::memory_usage();
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return bytes + cl_gpu_bytes();
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}
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/* ---------------------------------------------------------------------- */
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void PairCoulLongGPU::cpu_compute(int start, int inum, int eflag, 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, itable;
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double qtmp, xtmp, ytmp, ztmp, delx, dely, delz, ecoul, fpair;
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double fraction, table;
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double r, r2inv, forcecoul, factor_coul;
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double grij, expm2, prefactor, t, erfc;
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int *jlist;
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double rsq;
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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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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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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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r2inv = 1.0 / rsq;
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if (rsq < cut_coulsq) {
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if (!ncoultablebits || rsq <= tabinnersq) {
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r = sqrt(rsq);
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grij = g_ewald * r;
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expm2 = exp(-grij * grij);
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t = 1.0 / (1.0 + EWALD_P * grij);
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erfc = t * (A1 + t * (A2 + t * (A3 + t * (A4 + t * A5)))) * expm2;
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prefactor = qqrd2e * qtmp * q[j] / r;
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forcecoul = prefactor * (erfc + EWALD_F * grij * expm2);
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if (factor_coul < 1.0) forcecoul -= (1.0 - factor_coul) * prefactor;
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} else {
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union_int_float_t rsq_lookup;
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rsq_lookup.f = rsq;
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itable = rsq_lookup.i & ncoulmask;
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itable >>= ncoulshiftbits;
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fraction = (rsq_lookup.f - rtable[itable]) * drtable[itable];
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table = ftable[itable] + fraction * dftable[itable];
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forcecoul = qtmp * q[j] * table;
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if (factor_coul < 1.0) {
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table = ctable[itable] + fraction * dctable[itable];
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prefactor = qtmp * q[j] * table;
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forcecoul -= (1.0 - factor_coul) * prefactor;
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}
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}
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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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if (!ncoultablebits || rsq <= tabinnersq)
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ecoul = prefactor * erfc;
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else {
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table = etable[itable] + fraction * detable[itable];
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ecoul = qtmp * q[j] * table;
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}
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if (factor_coul < 1.0) ecoul -= (1.0 - factor_coul) * prefactor;
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} else
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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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