MD-Bench/lammps/thermo.c

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/*
* =======================================================================================
*
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* Author: Jan Eitzinger (je), jan.eitzinger@fau.de
* Copyright (c) 2020 RRZE, University Erlangen-Nuremberg
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*
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* This file is part of MD-Bench.
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*
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* 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.
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*
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* 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.
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*
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* 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/>.
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* =======================================================================================
*/
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <thermo.h>
#include <util.h>
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static int *steparr;
static MD_FLOAT *tmparr;
static MD_FLOAT *engarr;
static MD_FLOAT *prsarr;
static MD_FLOAT mvv2e;
static MD_FLOAT dof_boltz;
static MD_FLOAT t_scale;
static MD_FLOAT p_scale;
static MD_FLOAT e_scale;
static MD_FLOAT t_act;
static MD_FLOAT p_act;
static MD_FLOAT e_act;
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static int mstat;
/* exported subroutines */
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void setupThermo(Parameter *param, int natoms)
{
int maxstat = param->ntimes / param->nstat + 2;
steparr = (int*) malloc(maxstat * sizeof(int));
tmparr = (MD_FLOAT*) malloc(maxstat * sizeof(MD_FLOAT));
engarr = (MD_FLOAT*) malloc(maxstat * sizeof(MD_FLOAT));
prsarr = (MD_FLOAT*) malloc(maxstat * sizeof(MD_FLOAT));
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if(param->force_field == FF_LJ) {
mvv2e = 1.0;
dof_boltz = (natoms * 3 - 3);
t_scale = mvv2e / dof_boltz;
p_scale = 1.0 / 3 / param->xprd / param->yprd / param->zprd;
e_scale = 0.5;
} else {
mvv2e = 1.036427e-04;
dof_boltz = (natoms * 3 - 3) * 8.617343e-05;
t_scale = mvv2e / dof_boltz;
p_scale = 1.602176e+06 / 3 / param->xprd / param->yprd / param->zprd;
e_scale = 524287.985533;//16.0;
param->dtforce /= mvv2e;
}
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}
void computeThermo(int iflag, Parameter *param, Atom *atom)
{
MD_FLOAT t = 0.0, p;
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for(int i = 0; i < atom->Nlocal; i++) {
t += (atom_vx(i) * atom_vx(i) + atom_vy(i) * atom_vy(i) + atom_vz(i) * atom_vz(i)) * param->mass;
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}
t = t * t_scale;
p = (t * dof_boltz) * p_scale;
int istep = iflag;
if(iflag == -1){
istep = param->ntimes;
}
if(iflag == 0){
mstat = 0;
}
steparr[mstat] = istep;
tmparr[mstat] = t;
prsarr[mstat] = p;
mstat++;
fprintf(stdout, "%i\t%e\t%e\n", istep, t, p);
}
void adjustThermo(Parameter *param, Atom *atom)
{
/* zero center-of-mass motion */
MD_FLOAT vxtot = 0.0; MD_FLOAT vytot = 0.0; MD_FLOAT vztot = 0.0;
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for(int i = 0; i < atom->Nlocal; i++) {
vxtot += atom_vx(i);
vytot += atom_vy(i);
vztot += atom_vz(i);
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}
vxtot = vxtot / atom->Natoms;
vytot = vytot / atom->Natoms;
vztot = vztot / atom->Natoms;
for(int i = 0; i < atom->Nlocal; i++) {
atom_vx(i) -= vxtot;
atom_vy(i) -= vytot;
atom_vz(i) -= vztot;
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}
t_act = 0;
MD_FLOAT t = 0.0;
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for(int i = 0; i < atom->Nlocal; i++) {
t += (atom_vx(i) * atom_vx(i) + atom_vy(i) * atom_vy(i) + atom_vz(i) * atom_vz(i)) * param->mass;
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}
t *= t_scale;
MD_FLOAT factor = sqrt(param->temp / t);
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for(int i = 0; i < atom->Nlocal; i++) {
atom_vx(i) *= factor;
atom_vy(i) *= factor;
atom_vz(i) *= factor;
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}
}