MD-Bench/lammps/force_dem.c

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/*
* =======================================================================================
*
* Author: Jan Eitzinger (je), jan.eitzinger@fau.de
* Copyright (c) 2021 RRZE, University Erlangen-Nuremberg
*
* This file is part of MD-Bench.
*
* MD-Bench is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* MD-Bench is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
* details.
*
* You should have received a copy of the GNU Lesser General Public License along
* with MD-Bench. If not, see <https://www.gnu.org/licenses/>.
* =======================================================================================
*/
#include <math.h>
#include <likwid-marker.h>
#include <timing.h>
#include <neighbor.h>
#include <parameter.h>
#include <atom.h>
#include <stats.h>
// TODO: Joint common files for gromacs and lammps variants
#include "../gromacs/includes/simd.h"
double computeForceDemFullNeigh(Parameter *param, Atom *atom, Neighbor *neighbor, Stats *stats) {
int Nlocal = atom->Nlocal;
int* neighs;
MD_FLOAT k_s = param->k_s;
MD_FLOAT k_dn = param->k_dn;
MD_FLOAT cutforcesq = param->cutforce * param->cutforce;
for(int i = 0; i < Nlocal; i++) {
atom_fx(i) = 0.0;
atom_fy(i) = 0.0;
atom_fz(i) = 0.0;
}
double S = getTimeStamp();
LIKWID_MARKER_START("force");
for(int i = 0; i < Nlocal; i++) {
neighs = &neighbor->neighbors[i * neighbor->maxneighs];
int numneighs = neighbor->numneigh[i];
MD_FLOAT irad = atom->radius[i];
MD_FLOAT xtmp = atom_x(i);
MD_FLOAT ytmp = atom_y(i);
MD_FLOAT ztmp = atom_z(i);
MD_FLOAT fix = 0;
MD_FLOAT fiy = 0;
MD_FLOAT fiz = 0;
for(int k = 0; k < numneighs; k++) {
int j = neighs[k];
MD_FLOAT jrad = atom->radius[j];
MD_FLOAT xj = atom_x(j);
MD_FLOAT yj = atom_y(j);
MD_FLOAT zj = atom_z(j);
MD_FLOAT delx = xtmp - xj;
MD_FLOAT dely = ytmp - yj;
MD_FLOAT delz = ztmp - zj;
MD_FLOAT rsq = delx * delx + dely * dely + delz * delz;
if(rsq < cutforcesq) {
MD_FLOAT r = sqrt(rsq);
MD_FLOAT p = irad + jrad - r;
if(p > 0) {
MD_FLOAT delvx = atom_vx(i) - atom_vx(j);
MD_FLOAT delvy = atom_vy(i) - atom_vy(j);
MD_FLOAT delvz = atom_vz(i) - atom_vz(j);
MD_FLOAT vr = sqrt(delvx * delvx + delvy * delvy + delvz * delvz);
// normal distance
MD_FLOAT nx = delx / r;
MD_FLOAT ny = dely / r;
MD_FLOAT nz = delz / r;
// normal contact velocity
MD_FLOAT nvx = delvx / vr;
MD_FLOAT nvy = delvy / vr;
MD_FLOAT nvz = delvz / vr;
// forces
atom_fx(i) += k_s * p * nx - k_dn * nvx;
atom_fy(i) += k_s * p * ny - k_dn * nvy;
atom_fz(i) += k_s * p * nz - k_dn * nvz;
atom_fx(j) += -k_s * p * nx - k_dn * nvx;
atom_fy(j) += -k_s * p * ny - k_dn * nvy;
atom_fz(j) += -k_s * p * nz - k_dn * nvz;
// contact position
//MD_FLOAT cterm = jrad / (irad + jrad);
//MD_FLOAT cx = xj + cterm * delx;
//MD_FLOAT cy = yj + cterm * dely;
//MD_FLOAT cz = zj + cterm * delz;
// delta contact and particle position
//MD_FLOAT delcx = cx - xtmp;
//MD_FLOAT delcy = cy - ytmp;
//MD_FLOAT delcz = cz - ztmp;
// contact velocity
//MD_FLOAT cvx = (atom_vx(i) + atom_avx(i) * delcx) - (atom_vx(j) + atom_avx(j) * (cx - xj));
//MD_FLOAT cvy = (atom_vy(i) + atom_avy(i) * delcy) - (atom_vy(j) + atom_avy(j) * (cy - yj));
//MD_FLOAT cvz = (atom_vz(i) + atom_avz(i) * delcz) - (atom_vz(j) + atom_avz(j) * (cz - zj));
// tangential force
//fix += MIN(kdt * vtsq, kf * fnx) * tx;
//fiy += MIN(kdt * vtsq, kf * fny) * ty;
//fiz += MIN(kdt * vtsq, kf * fnz) * tz;
// torque
//MD_FLOAT taux = delcx * ftx;
//MD_FLOAT tauy = delcy * fty;
//MD_FLOAT tauz = delcz * ftz;
}
#ifdef USE_REFERENCE_VERSION
addStat(stats->atoms_within_cutoff, 1);
} else {
addStat(stats->atoms_outside_cutoff, 1);
#endif
}
}
addStat(stats->total_force_neighs, numneighs);
addStat(stats->total_force_iters, (numneighs + VECTOR_WIDTH - 1) / VECTOR_WIDTH);
}
LIKWID_MARKER_STOP("force");
double E = getTimeStamp();
return E-S;
}