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lammps/src/USER-REAXC/reaxc_nonbonded.cpp
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/*----------------------------------------------------------------------
PuReMD - Purdue ReaxFF Molecular Dynamics Program
Copyright (2010) Purdue University
Hasan Metin Aktulga, hmaktulga@lbl.gov
Joseph Fogarty, jcfogart@mail.usf.edu
Sagar Pandit, pandit@usf.edu
Ananth Y Grama, ayg@cs.purdue.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, in press.
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:
<http://www.gnu.org/licenses/>.
----------------------------------------------------------------------*/
#include "pair_reax_c.h"
#include "reaxc_types.h"
#if defined(PURE_REAX)
#include "nonbonded.h"
#include "bond_orders.h"
#include "list.h"
#include "vector.h"
#elif defined(LAMMPS_REAX)
#include "reaxc_nonbonded.h"
#include "reaxc_bond_orders.h"
#include "reaxc_list.h"
#include "reaxc_vector.h"
#endif
void vdW_Coulomb_Energy( reax_system *system, control_params *control,
simulation_data *data, storage *workspace,
reax_list **lists, output_controls *out_control )
{
int i, j, pj, natoms;
int start_i, end_i, orig_i, orig_j, flag;
real p_vdW1, p_vdW1i;
real powr_vdW1, powgi_vdW1;
real tmp, r_ij, fn13, exp1, exp2;
real Tap, dTap, dfn13, CEvd, CEclmb, de_core;
real dr3gamij_1, dr3gamij_3;
real e_ele, e_vdW, e_core, SMALL = 0.0001;
rvec temp, ext_press;
two_body_parameters *twbp;
far_neighbor_data *nbr_pj;
reax_list *far_nbrs;
// rtensor temp_rtensor, total_rtensor;
// Tallying variables:
real pe_vdw, f_tmp, delij[3];
natoms = system->n;
far_nbrs = (*lists) + FAR_NBRS;
p_vdW1 = system->reax_param.gp.l[28];
p_vdW1i = 1.0 / p_vdW1;
e_core = 0;
e_vdW = 0;
for( i = 0; i < natoms; ++i ) {
start_i = Start_Index(i, far_nbrs);
end_i = End_Index(i, far_nbrs);
orig_i = system->my_atoms[i].orig_id;
//fprintf( stderr, "i:%d, start_i: %d, end_i: %d\n", i, start_i, end_i );
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;
#if defined(PURE_REAX)
if( nbr_pj->d <= control->nonb_cut && (j < natoms || orig_i < orig_j) ) {
#elif defined(LAMMPS_REAX)
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) {
#endif
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);
data->my_en.e_vdW += 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);
data->my_en.e_vdW += 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)));
data->my_en.e_vdW += Tap * e_core;
de_core = -(twbp->acore/twbp->rcore) * e_core;
CEvd += dTap * e_core + Tap * de_core / 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;
data->my_en.e_ele += 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->evflag || system->vflag_atom) {
pe_vdw = Tap * (e_vdW + e_core);
rvec_ScaledSum( delij, 1., system->my_atoms[i].x,
-1., system->my_atoms[j].x );
f_tmp = -(CEvd + CEclmb);
system->pair_ptr->ev_tally(i,j,natoms,1,pe_vdw,e_ele,
f_tmp,delij[0],delij[1],delij[2]);
}
/* fprintf(stderr, "%5d %5d %10.6f %10.6f\n",
MIN( system->my_atoms[i].orig_id, system->my_atoms[j].orig_id ),
MAX( system->my_atoms[i].orig_id, system->my_atoms[j].orig_id ),
CEvd, CEclmb ); */
if( control->virial == 0 ) {
rvec_ScaledAdd( workspace->f[i], -(CEvd + CEclmb), nbr_pj->dvec );
rvec_ScaledAdd( workspace->f[j], +(CEvd + CEclmb), nbr_pj->dvec );
}
else { /* NPT, iNPT or sNPT */
/* for pressure coupling, terms not related to bond order
derivatives are added directly into pressure vector/tensor */
rvec_Scale( temp, CEvd + CEclmb, nbr_pj->dvec );
rvec_ScaledAdd( workspace->f[i], -1., temp );
rvec_Add( workspace->f[j], temp );
rvec_iMultiply( ext_press, nbr_pj->rel_box, temp );
rvec_Add( data->my_ext_press, ext_press );
/* fprintf( stderr, "nonbonded(%d,%d): rel_box (%f %f %f)
force(%f %f %f) ext_press (%12.6f %12.6f %12.6f)\n",
i, j, nbr_pj->rel_box[0], nbr_pj->rel_box[1], nbr_pj->rel_box[2],
temp[0], temp[1], temp[2],
data->ext_press[0], data->ext_press[1], data->ext_press[2] ); */
}
#ifdef TEST_ENERGY
// fprintf( out_control->evdw,
// "%12.9f%12.9f%12.9f%12.9f%12.9f%12.9f%12.9f%12.9f\n",
// workspace->Tap[7],workspace->Tap[6],workspace->Tap[5],
// workspace->Tap[4],workspace->Tap[3],workspace->Tap[2],
// workspace->Tap[1], Tap );
//fprintf( out_control->evdw, "%6d%6d%24.15e%24.15e%24.15e\n",
fprintf( out_control->evdw, "%6d%6d%12.4f%12.4f%12.4f\n",
system->my_atoms[i].orig_id, system->my_atoms[j].orig_id,
r_ij, e_vdW, data->my_en.e_vdW );
//fprintf(out_control->ecou,"%6d%6d%24.15e%24.15e%24.15e%24.15e%24.15e\n",
fprintf( out_control->ecou, "%6d%6d%12.4f%12.4f%12.4f%12.4f%12.4f\n",
system->my_atoms[i].orig_id, system->my_atoms[j].orig_id,
r_ij, system->my_atoms[i].q, system->my_atoms[j].q,
e_ele, data->my_en.e_ele );
#endif
#ifdef TEST_FORCES
rvec_ScaledAdd( workspace->f_vdw[i], -CEvd, nbr_pj->dvec );
rvec_ScaledAdd( workspace->f_vdw[j], +CEvd, nbr_pj->dvec );
rvec_ScaledAdd( workspace->f_ele[i], -CEclmb, nbr_pj->dvec );
rvec_ScaledAdd( workspace->f_ele[j], +CEclmb, nbr_pj->dvec );
#endif
}
}
}
#if defined(DEBUG)
fprintf( stderr, "nonbonded: ext_press (%12.6f %12.6f %12.6f)\n",
data->ext_press[0], data->ext_press[1], data->ext_press[2] );
MPI_Barrier( MPI_COMM_WORLD );
#endif
Compute_Polarization_Energy( system, data );
}
void Tabulated_vdW_Coulomb_Energy( reax_system *system,control_params *control,
simulation_data *data, storage *workspace,
reax_list **lists,
output_controls *out_control )
{
int i, j, pj, r, natoms, steps, update_freq, update_energies;
int type_i, type_j, tmin, tmax;
int start_i, end_i, orig_i, orig_j, flag;
real r_ij, base, dif;
real e_vdW, e_ele;
real CEvd, CEclmb, SMALL = 0.0001;
real f_tmp, delij[3];
rvec temp, ext_press;
far_neighbor_data *nbr_pj;
reax_list *far_nbrs;
LR_lookup_table *t;
natoms = system->n;
far_nbrs = (*lists) + FAR_NBRS;
steps = data->step - data->prev_steps;
update_freq = out_control->energy_update_freq;
update_energies = update_freq > 0 && steps % update_freq == 0;
e_ele = e_vdW = 0;
for( i = 0; i < natoms; ++i ) {
type_i = system->my_atoms[i].type;
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;
#if defined(PURE_REAX)
if( nbr_pj->d <= control->nonb_cut && (j < natoms || orig_i < orig_j) ) {
#elif defined(LAMMPS_REAX)
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) {
#endif
j = nbr_pj->nbr;
type_j = system->my_atoms[j].type;
r_ij = nbr_pj->d;
tmin = MIN( type_i, type_j );
tmax = MAX( type_i, type_j );
t = &( LR[tmin][tmax] );
//t = &( LR[type_i][type_j] );
/* Cubic Spline Interpolation */
r = (int)(r_ij * t->inv_dx);
if( r == 0 ) ++r;
base = (real)(r+1) * t->dx;
dif = r_ij - base;
//fprintf(stderr, "r: %f, i: %d, base: %f, dif: %f\n", r, i, base, dif);
if( update_energies ) {
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;
data->my_en.e_vdW += e_vdW;
data->my_en.e_ele += 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->evflag || system->vflag_atom) {
rvec_ScaledSum( delij, 1., system->my_atoms[i].x,
-1., system->my_atoms[j].x );
f_tmp = -(CEvd + CEclmb);
system->pair_ptr->ev_tally(i,j,natoms,1,e_vdW,e_ele,
f_tmp,delij[0],delij[1],delij[2]);
}
if( control->virial == 0 ) {
rvec_ScaledAdd( workspace->f[i], -(CEvd + CEclmb), nbr_pj->dvec );
rvec_ScaledAdd( workspace->f[j], +(CEvd + CEclmb), nbr_pj->dvec );
}
else { // NPT, iNPT or sNPT
/* for pressure coupling, terms not related to bond order derivatives
are added directly into pressure vector/tensor */
rvec_Scale( temp, CEvd + CEclmb, nbr_pj->dvec );
rvec_ScaledAdd( workspace->f[i], -1., temp );
rvec_Add( workspace->f[j], temp );
rvec_iMultiply( ext_press, nbr_pj->rel_box, temp );
rvec_Add( data->my_ext_press, ext_press );
}
#ifdef TEST_ENERGY
//fprintf( out_control->evdw, "%6d%6d%24.15e%24.15e%24.15e\n",
fprintf( out_control->evdw, "%6d%6d%12.4f%12.4f%12.4f\n",
system->my_atoms[i].orig_id, system->my_atoms[j].orig_id,
r_ij, e_vdW, data->my_en.e_vdW );
//fprintf(out_control->ecou,"%6d%6d%24.15e%24.15e%24.15e%24.15e%24.15e\n",
fprintf( out_control->ecou, "%6d%6d%12.4f%12.4f%12.4f%12.4f%12.4f\n",
system->my_atoms[i].orig_id, system->my_atoms[j].orig_id,
r_ij, system->my_atoms[i].q, system->my_atoms[j].q,
e_ele, data->my_en.e_ele );
#endif
#ifdef TEST_FORCES
rvec_ScaledAdd( workspace->f_vdw[i], -CEvd, nbr_pj->dvec );
rvec_ScaledAdd( workspace->f_vdw[j], +CEvd, nbr_pj->dvec );
rvec_ScaledAdd( workspace->f_ele[i], -CEclmb, nbr_pj->dvec );
rvec_ScaledAdd( workspace->f_ele[j], +CEclmb, nbr_pj->dvec );
#endif
}
}
}
Compute_Polarization_Energy( system, data );
}
void Compute_Polarization_Energy( reax_system *system, simulation_data *data )
{
int i, type_i;
real q, en_tmp;
data->my_en.e_pol = 0.0;
for( i = 0; i < system->n; i++ ) {
q = system->my_atoms[i].q;
type_i = system->my_atoms[i].type;
en_tmp = KCALpMOL_to_EV * (system->reax_param.sbp[type_i].chi * q +
(system->reax_param.sbp[type_i].eta / 2.) * SQR(q));
data->my_en.e_pol += en_tmp;
/* tally into per-atom energy */
if( system->evflag)
system->pair_ptr->ev_tally(i,i,system->n,1,0.0,en_tmp,0.0,0.0,0.0,0.0);
}
}
void LR_vdW_Coulomb( reax_system *system, storage *workspace,
int i, int j, real r_ij, LR_data *lr )
{
real p_vdW1 = system->reax_param.gp.l[28];
real p_vdW1i = 1.0 / p_vdW1;
real powr_vdW1, powgi_vdW1;
real tmp, fn13, exp1, exp2;
real Tap, dTap, dfn13;
real dr3gamij_1, dr3gamij_3;
real e_core, de_core;
two_body_parameters *twbp;
twbp = &(system->reax_param.tbp[i][j]);
e_core = 0;
de_core = 0;
/* calculate taper and its derivative */
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) );
lr->e_vdW = Tap * twbp->D * (exp1 - 2.0 * exp2);
dfn13 = pow( powr_vdW1 + powgi_vdW1, p_vdW1i-1.0) * pow(r_ij, p_vdW1-2.0);
lr->CEvd = dTap * twbp->D * (exp1 - 2.0 * exp2) -
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) );
lr->e_vdW = Tap * twbp->D * (exp1 - 2.0 * exp2);
lr->CEvd = dTap * twbp->D * (exp1 - 2.0 * exp2) -
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)));
lr->e_vdW += Tap * e_core;
de_core = -(twbp->acore/twbp->rcore) * e_core;
lr->CEvd += dTap * e_core + Tap * de_core / 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;
lr->H = EV_to_KCALpMOL * tmp;
lr->e_ele = C_ele * tmp;
// fprintf( stderr,
// "i:%d(%d), j:%d(%d), gamma:%f, Tap:%f, dr3gamij_3:%f, qi: %f, qj: %f\n",
// i, system->my_atoms[i].type, j, system->my_atoms[j].type,
// twbp->gamma, Tap, dr3gamij_3,
// system->my_atoms[i].q, system->my_atoms[j].q );
lr->CEclmb = C_ele * ( dTap - Tap * r_ij / dr3gamij_1 ) / dr3gamij_3;
// fprintf( stdout, "%d %d\t%g\t%g %g\t%g %g\t%g %g\n",
// i+1, j+1, r_ij, e_vdW, CEvd * r_ij,
// system->my_atoms[i].q, system->my_atoms[j].q, e_ele, CEclmb * r_ij );
// fprintf(stderr,"LR_Lookup: %3d %3d %5.3f-%8.5f %8.5f %8.5f %8.5f %8.5f\n",
// i, j, r_ij, lr->H, lr->e_vdW, lr->CEvd, lr->e_ele, lr->CEclmb ); */
}
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