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lammps/src/OPENMP/reaxff_nonbonded_omp.cpp

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// clang-format off
/*----------------------------------------------------------------------
PuReMD - Purdue ReaxFF Molecular Dynamics Program
Website: https://www.cs.purdue.edu/puremd
Copyright (2010) Purdue University
Contributing authors:
H. M. Aktulga, J. Fogarty, S. Pandit, A. Grama
Corresponding author:
Hasan Metin Aktulga, Michigan State University, hma@cse.msu.edu
Please cite the related publication:
H. M. Aktulga, J. C. Fogarty, S. A. Pandit, A. Y. Grama,
"Parallel Reactive Molecular Dynamics: Numerical Methods and
Algorithmic Techniques", Parallel Computing, 38 (4-5), 245-259
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.
This program 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 General Public License for more details:
<https://www.gnu.org/licenses/>.
----------------------------------------------------------------------*/
#include "reaxff_omp.h"
#include "pair_reaxff_omp.h"
#include "reaxff_api.h"
#include <cmath>
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
namespace ReaxFF {
void vdW_Coulomb_Energy_OMP(reax_system *system, control_params *control,
simulation_data *data, storage *workspace,
reax_list **lists)
{
int natoms = system->n;
reax_list *far_nbrs = (*lists) + FAR_NBRS;
double p_vdW1 = system->reax_param.gp.l[28];
double p_vdW1i = 1.0 / p_vdW1;
double total_EvdW = 0.;
double total_Eele = 0.;
#if defined(_OPENMP)
#pragma omp parallel default(shared) reduction(+: total_EvdW, total_Eele)
#endif
{
int tid = get_tid();
int i, j, pj;
int start_i, end_i, orig_i, orig_j, flag;
double powr_vdW1, powgi_vdW1;
double tmp, r_ij, fn13, exp1, exp2;
double Tap, dTap, dfn13, CEvd, CEclmb, de_core;
double dr3gamij_1, dr3gamij_3;
double e_ele, e_vdW, e_core;
const double SMALL = 0.0001;
double e_lg, de_lg, r_ij5, r_ij6, re6;
two_body_parameters *twbp;
far_neighbor_data *nbr_pj;
// Tallying variables:
double pe_vdw, f_tmp, delij[3];
long reductionOffset = (system->N * tid);
class PairReaxFFOMP *pair_reax_ptr;
pair_reax_ptr = static_cast<class PairReaxFFOMP*>(system->pair_ptr);
class ThrData *thr = pair_reax_ptr->getFixOMP()->get_thr(tid);
e_core = 0;
e_vdW = 0;
e_lg = 0;
de_lg = 0.0;
#if defined(_OPENMP)
#pragma omp for schedule(guided)
#endif
for (i = 0; i < natoms; ++i) {
if (system->my_atoms[i].type < 0) continue;
start_i = Start_Index(i, far_nbrs);
end_i = End_Index(i, far_nbrs);
orig_i = system->my_atoms[i].orig_id;
for (pj = start_i; pj < end_i; ++pj) {
nbr_pj = &(far_nbrs->select.far_nbr_list[pj]);
j = nbr_pj->nbr;
orig_j = system->my_atoms[j].orig_id;
flag = 0;
if (nbr_pj->d <= control->nonb_cut) {
if (j < natoms) flag = 1;
else if (orig_i < orig_j) flag = 1;
else if (orig_i == orig_j) {
if (nbr_pj->dvec[2] > SMALL) flag = 1;
else if (fabs(nbr_pj->dvec[2]) < SMALL) {
if (nbr_pj->dvec[1] > SMALL) flag = 1;
else if (fabs(nbr_pj->dvec[1]) < SMALL && nbr_pj->dvec[0] > SMALL)
flag = 1;
}
}
}
if (flag) {
r_ij = nbr_pj->d;
twbp = &(system->reax_param.tbp[system->my_atoms[i].type]
[system->my_atoms[j].type]);
/* Calculate Taper and its derivative */
// Tap = nbr_pj->Tap; -- precomputed during compte_H
Tap = workspace->Tap[7] * r_ij + workspace->Tap[6];
Tap = Tap * r_ij + workspace->Tap[5];
Tap = Tap * r_ij + workspace->Tap[4];
Tap = Tap * r_ij + workspace->Tap[3];
Tap = Tap * r_ij + workspace->Tap[2];
Tap = Tap * r_ij + workspace->Tap[1];
Tap = Tap * r_ij + workspace->Tap[0];
dTap = 7*workspace->Tap[7] * r_ij + 6*workspace->Tap[6];
dTap = dTap * r_ij + 5*workspace->Tap[5];
dTap = dTap * r_ij + 4*workspace->Tap[4];
dTap = dTap * r_ij + 3*workspace->Tap[3];
dTap = dTap * r_ij + 2*workspace->Tap[2];
dTap += workspace->Tap[1]/r_ij;
/*vdWaals Calculations*/
if (system->reax_param.gp.vdw_type==1 || system->reax_param.gp.vdw_type==3)
{ // shielding
powr_vdW1 = pow(r_ij, p_vdW1);
powgi_vdW1 = pow(1.0 / twbp->gamma_w, p_vdW1);
fn13 = pow(powr_vdW1 + powgi_vdW1, p_vdW1i);
exp1 = exp(twbp->alpha * (1.0 - fn13 / twbp->r_vdW));
exp2 = exp(0.5 * twbp->alpha * (1.0 - fn13 / twbp->r_vdW));
e_vdW = twbp->D * (exp1 - 2.0 * exp2);
total_EvdW += Tap * e_vdW;
dfn13 = pow(powr_vdW1 + powgi_vdW1, p_vdW1i - 1.0) *
pow(r_ij, p_vdW1 - 2.0);
CEvd = dTap * e_vdW -
Tap * twbp->D * (twbp->alpha / twbp->r_vdW) * (exp1 - exp2) * dfn13;
}
else { // no shielding
exp1 = exp(twbp->alpha * (1.0 - r_ij / twbp->r_vdW));
exp2 = exp(0.5 * twbp->alpha * (1.0 - r_ij / twbp->r_vdW));
e_vdW = twbp->D * (exp1 - 2.0 * exp2);
total_EvdW += Tap * e_vdW;
CEvd = dTap * e_vdW -
Tap * twbp->D * (twbp->alpha / twbp->r_vdW) * (exp1 - exp2) / r_ij;
}
if (system->reax_param.gp.vdw_type==2 || system->reax_param.gp.vdw_type==3)
{ // innner wall
e_core = twbp->ecore * exp(twbp->acore * (1.0-(r_ij/twbp->rcore)));
total_EvdW += Tap * e_core;
de_core = -(twbp->acore/twbp->rcore) * e_core;
CEvd += dTap * e_core + Tap * de_core / r_ij;
// lg correction, only if lgvdw is yes
if (control->lgflag) {
r_ij5 = pow(r_ij, 5.0);
r_ij6 = pow(r_ij, 6.0);
re6 = pow(twbp->lgre, 6.0);
e_lg = -(twbp->lgcij/(r_ij6 + re6));
total_EvdW += Tap * e_lg;
de_lg = -6.0 * e_lg * r_ij5 / (r_ij6 + re6) ;
CEvd += dTap * e_lg + Tap * de_lg / r_ij;
}
}
/*Coulomb Calculations*/
dr3gamij_1 = (r_ij * r_ij * r_ij + twbp->gamma);
dr3gamij_3 = pow(dr3gamij_1 , 0.33333333333333);
tmp = Tap / dr3gamij_3;
total_Eele += e_ele =
C_ele * system->my_atoms[i].q * system->my_atoms[j].q * tmp;
CEclmb = C_ele * system->my_atoms[i].q * system->my_atoms[j].q *
(dTap - Tap * r_ij / dr3gamij_1) / dr3gamij_3;
/* tally into per-atom energy */
if (system->pair_ptr->evflag || system->pair_ptr->vflag_atom) {
pe_vdw = Tap * (e_vdW + e_core + e_lg);
rvec_ScaledSum(delij, 1., system->my_atoms[i].x,
-1., system->my_atoms[j].x);
f_tmp = -(CEvd + CEclmb);
pair_reax_ptr->ev_tally_thr_proxy( i, j, natoms,
1, pe_vdw, e_ele, f_tmp,
delij[0], delij[1], delij[2], thr);
}
rvec_ScaledAdd(workspace->f[i], -(CEvd + CEclmb), nbr_pj->dvec);
rvec_ScaledAdd(workspace->forceReduction[reductionOffset+j],
+(CEvd + CEclmb), nbr_pj->dvec);
}
}
}
pair_reax_ptr->reduce_thr_proxy(system->pair_ptr, system->pair_ptr->eflag_either,
system->pair_ptr->vflag_either, thr);
} // parallel region
data->my_en.e_vdW = total_EvdW;
data->my_en.e_ele = total_Eele;
Compute_Polarization_Energy(system, data, workspace);
}
/* ---------------------------------------------------------------------- */
void Tabulated_vdW_Coulomb_Energy_OMP(reax_system *system,control_params *control,
simulation_data *data, storage *workspace,
reax_list **lists) {
double SMALL = 0.0001;
int natoms = system->n;
reax_list *far_nbrs = (*lists) + FAR_NBRS;
double total_EvdW = 0.;
double total_Eele = 0.;
#if defined(_OPENMP)
#pragma omp parallel default(shared) reduction(+:total_EvdW, total_Eele)
#endif
{
int i, j, pj, r;
int type_i, type_j, tmin, tmax;
int start_i, end_i, orig_i, orig_j, flag;
double r_ij, base, dif;
double e_vdW, e_ele;
double CEvd, CEclmb;
double f_tmp, delij[3];
far_neighbor_data *nbr_pj;
LR_lookup_table *t;
int tid = get_tid();
long froffset = (system->N * tid);
LR_lookup_table ** & LR = system->LR;
class PairReaxFFOMP *pair_reax_ptr;
pair_reax_ptr = static_cast<class PairReaxFFOMP*>(system->pair_ptr);
class ThrData *thr = pair_reax_ptr->getFixOMP()->get_thr(tid);
#if defined(_OPENMP)
#pragma omp for schedule(guided)
#endif
for (i = 0; i < natoms; ++i) {
type_i = system->my_atoms[i].type;
if (type_i < 0) continue;
start_i = Start_Index(i,far_nbrs);
end_i = End_Index(i,far_nbrs);
orig_i = system->my_atoms[i].orig_id;
for (pj = start_i; pj < end_i; ++pj) {
nbr_pj = &(far_nbrs->select.far_nbr_list[pj]);
j = nbr_pj->nbr;
type_j = system->my_atoms[j].type;
if (type_j < 0) continue;
orig_j = system->my_atoms[j].orig_id;
flag = 0;
if (nbr_pj->d <= control->nonb_cut) {
if (j < natoms) flag = 1;
else if (orig_i < orig_j) flag = 1;
else if (orig_i == orig_j) {
if (nbr_pj->dvec[2] > SMALL) flag = 1;
else if (fabs(nbr_pj->dvec[2]) < SMALL) {
if (nbr_pj->dvec[1] > SMALL) flag = 1;
else if (fabs(nbr_pj->dvec[1]) < SMALL && nbr_pj->dvec[0] > SMALL)
flag = 1;
}
}
}
if (flag) {
r_ij = nbr_pj->d;
tmin = MIN(type_i, type_j);
tmax = MAX(type_i, type_j);
t = &(LR[tmin][tmax]);
/* Cubic Spline Interpolation */
r = (int)(r_ij * t->inv_dx);
if (r == 0) ++r;
base = (double)(r+1) * t->dx;
dif = r_ij - base;
e_vdW = ((t->vdW[r].d*dif + t->vdW[r].c)*dif + t->vdW[r].b)*dif +
t->vdW[r].a;
e_ele = ((t->ele[r].d*dif + t->ele[r].c)*dif + t->ele[r].b)*dif +
t->ele[r].a;
e_ele *= system->my_atoms[i].q * system->my_atoms[j].q;
total_EvdW += e_vdW;
total_Eele += e_ele;
CEvd = ((t->CEvd[r].d*dif + t->CEvd[r].c)*dif + t->CEvd[r].b)*dif +
t->CEvd[r].a;
CEclmb = ((t->CEclmb[r].d*dif+t->CEclmb[r].c)*dif+t->CEclmb[r].b)*dif +
t->CEclmb[r].a;
CEclmb *= system->my_atoms[i].q * system->my_atoms[j].q;
/* tally into per-atom energy */
if (system->pair_ptr->evflag) {
rvec_ScaledSum(delij, 1., system->my_atoms[i].x,
-1., system->my_atoms[j].x);
f_tmp = -(CEvd + CEclmb);
pair_reax_ptr->ev_tally_thr_proxy( i, j, natoms, 1, e_vdW, e_ele,
f_tmp, delij[0], delij[1], delij[2], thr);
}
rvec_ScaledAdd(workspace->f[i], -(CEvd + CEclmb), nbr_pj->dvec);
rvec_ScaledAdd(workspace->forceReduction[froffset+j],
+(CEvd + CEclmb), nbr_pj->dvec);
}
}
}
pair_reax_ptr->reduce_thr_proxy(system->pair_ptr, system->pair_ptr->eflag_either,
system->pair_ptr->vflag_either, thr);
} // end omp parallel
data->my_en.e_vdW = total_EvdW;
data->my_en.e_ele = total_Eele;
Compute_Polarization_Energy(system, data, workspace);
}
}