forked from lijiext/lammps
173 lines
4.4 KiB
C++
173 lines
4.4 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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#include "stdio.h"
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#include "string.h"
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#include "fix_nve.h"
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#include "atom.h"
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#include "force.h"
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#include "update.h"
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#include "respa.h"
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#include "error.h"
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using namespace LAMMPS_NS;
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using namespace FixConst;
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/* ---------------------------------------------------------------------- */
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FixNVE::FixNVE(LAMMPS *lmp, int narg, char **arg) :
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Fix(lmp, narg, arg)
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{
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if (strcmp(style,"nve/sphere") != 0 && narg < 3)
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error->all(FLERR,"Illegal fix nve command");
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dynamic_group_allow = 1;
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time_integrate = 1;
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}
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/* ---------------------------------------------------------------------- */
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int FixNVE::setmask()
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{
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int mask = 0;
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mask |= INITIAL_INTEGRATE;
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mask |= FINAL_INTEGRATE;
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mask |= INITIAL_INTEGRATE_RESPA;
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mask |= FINAL_INTEGRATE_RESPA;
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return mask;
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}
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/* ---------------------------------------------------------------------- */
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void FixNVE::init()
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{
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dtv = update->dt;
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dtf = 0.5 * update->dt * force->ftm2v;
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if (strstr(update->integrate_style,"respa"))
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step_respa = ((Respa *) update->integrate)->step;
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}
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/* ----------------------------------------------------------------------
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allow for both per-type and per-atom mass
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------------------------------------------------------------------------- */
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void FixNVE::initial_integrate(int vflag)
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{
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double dtfm;
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// update v and x of atoms in group
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double **x = atom->x;
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double **v = atom->v;
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double **f = atom->f;
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double *rmass = atom->rmass;
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double *mass = atom->mass;
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int *type = atom->type;
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int *mask = atom->mask;
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int nlocal = atom->nlocal;
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if (igroup == atom->firstgroup) nlocal = atom->nfirst;
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if (rmass) {
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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dtfm = dtf / rmass[i];
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v[i][0] += dtfm * f[i][0];
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v[i][1] += dtfm * f[i][1];
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v[i][2] += dtfm * f[i][2];
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x[i][0] += dtv * v[i][0];
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x[i][1] += dtv * v[i][1];
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x[i][2] += dtv * v[i][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) {
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dtfm = dtf / mass[type[i]];
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v[i][0] += dtfm * f[i][0];
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v[i][1] += dtfm * f[i][1];
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v[i][2] += dtfm * f[i][2];
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x[i][0] += dtv * v[i][0];
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x[i][1] += dtv * v[i][1];
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x[i][2] += dtv * v[i][2];
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}
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixNVE::final_integrate()
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{
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double dtfm;
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// update v of atoms in group
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double **v = atom->v;
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double **f = atom->f;
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double *rmass = atom->rmass;
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double *mass = atom->mass;
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int *type = atom->type;
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int *mask = atom->mask;
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int nlocal = atom->nlocal;
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if (igroup == atom->firstgroup) nlocal = atom->nfirst;
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if (rmass) {
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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dtfm = dtf / rmass[i];
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v[i][0] += dtfm * f[i][0];
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v[i][1] += dtfm * f[i][1];
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v[i][2] += dtfm * f[i][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) {
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dtfm = dtf / mass[type[i]];
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v[i][0] += dtfm * f[i][0];
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v[i][1] += dtfm * f[i][1];
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v[i][2] += dtfm * f[i][2];
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}
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixNVE::initial_integrate_respa(int vflag, int ilevel, int iloop)
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{
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dtv = step_respa[ilevel];
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dtf = 0.5 * step_respa[ilevel] * force->ftm2v;
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// innermost level - NVE update of v and x
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// all other levels - NVE update of v
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if (ilevel == 0) initial_integrate(vflag);
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else final_integrate();
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}
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/* ---------------------------------------------------------------------- */
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void FixNVE::final_integrate_respa(int ilevel, int iloop)
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{
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dtf = 0.5 * step_respa[ilevel] * force->ftm2v;
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final_integrate();
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}
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/* ---------------------------------------------------------------------- */
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void FixNVE::reset_dt()
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{
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dtv = update->dt;
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dtf = 0.5 * update->dt * force->ftm2v;
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}
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