forked from lijiext/lammps
159 lines
4.3 KiB
C++
159 lines
4.3 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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http://lammps.sandia.gov, 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: Paul Crozier (SNL)
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------------------------------------------------------------------------- */
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#include "math.h"
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#include "stdlib.h"
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#include "string.h"
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#include "fix_heat.h"
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#include "atom.h"
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#include "domain.h"
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#include "region.h"
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#include "group.h"
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#include "force.h"
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#include "update.h"
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#include "error.h"
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using namespace LAMMPS_NS;
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/* ---------------------------------------------------------------------- */
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FixHeat::FixHeat(LAMMPS *lmp, int narg, char **arg) : Fix(lmp, narg, arg)
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{
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if (narg < 4) error->all("Illegal fix heat command");
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scalar_flag = 1;
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global_freq = 1;
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extscalar = 0;
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nevery = atoi(arg[3]);
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if (nevery <= 0) error->all("Illegal fix heat command");
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heat_input = atof(arg[4]);
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// optional args
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iregion = -1;
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idregion = NULL;
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int iarg = 5;
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while (iarg < narg) {
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if (strcmp(arg[iarg],"region") == 0) {
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if (iarg+2 > narg) error->all("Illegal fix heat command");
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iregion = domain->find_region(arg[iarg+1]);
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if (iregion == -1) error->all("Region ID for fix heat does not exist");
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int n = strlen(arg[iarg+1]) + 1;
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idregion = new char[n];
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strcpy(idregion,arg[iarg+1]);
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iarg += 2;
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} else error->all("Illegal fix heat command");
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}
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scale = 1.0;
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}
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/* ---------------------------------------------------------------------- */
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FixHeat::~FixHeat()
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{
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delete [] idregion;
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}
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/* ---------------------------------------------------------------------- */
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int FixHeat::setmask()
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{
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int mask = 0;
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mask |= END_OF_STEP;
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return mask;
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}
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/* ---------------------------------------------------------------------- */
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void FixHeat::init()
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{
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// set index and check validity of region
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if (iregion >= 0) {
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iregion = domain->find_region(idregion);
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if (iregion == -1) error->all("Region ID for fix heat does not exist");
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}
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// cannot have 0 atoms in group
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if (group->count(igroup) == 0) error->all("Fix heat group has no atoms");
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masstotal = group->mass(igroup);
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}
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/* ---------------------------------------------------------------------- */
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void FixHeat::end_of_step()
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{
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double heat,ke;
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double vsub[3],vcm[3];
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Region *region = NULL;
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if (iregion >= 0) region = domain->regions[iregion];
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if (iregion < 0) {
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heat = heat_input*nevery*update->dt*force->ftm2v;
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ke = group->ke(igroup)*force->ftm2v;
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group->vcm(igroup,masstotal,vcm);
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} else {
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masstotal = group->mass(igroup,iregion);
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if (masstotal == 0.0) error->all("Fix heat group has no atoms");
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heat = heat_input*nevery*update->dt*force->ftm2v;
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ke = group->ke(igroup,iregion)*force->ftm2v;
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group->vcm(igroup,masstotal,vcm,iregion);
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}
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double vcmsq = vcm[0]*vcm[0] + vcm[1]*vcm[1] + vcm[2]*vcm[2];
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double escale = (ke + heat - 0.5*vcmsq*masstotal)/(ke - 0.5*vcmsq*masstotal);
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if (escale < 0.0) error->all("Fix heat kinetic energy went negative");
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scale = sqrt(escale);
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vsub[0] = (scale-1.0) * vcm[0];
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vsub[1] = (scale-1.0) * vcm[1];
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vsub[2] = (scale-1.0) * vcm[2];
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double **x = atom->x;
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double **v = atom->v;
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int *mask = atom->mask;
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int nlocal = atom->nlocal;
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if (iregion < 0) {
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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v[i][0] = scale*v[i][0] - vsub[0];
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v[i][1] = scale*v[i][1] - vsub[1];
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v[i][2] = scale*v[i][2] - vsub[2];
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}
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} else {
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit && region->match(x[i][0],x[i][1],x[i][2])) {
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v[i][0] = scale*v[i][0] - vsub[0];
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v[i][1] = scale*v[i][1] - vsub[1];
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v[i][2] = scale*v[i][2] - vsub[2];
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}
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}
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}
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/* ---------------------------------------------------------------------- */
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double FixHeat::compute_scalar()
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{
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return scale;
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}
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