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USER-DPD: Added support to use VV integrator with USER-DPD if desired.

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Includes documentation and examples.
NOTE: VV requires very small timesteps under isoenergetic conditions.
Consider using fix_shardlow instead, since this VV support is
primarily for comparison purposes.
This commit is contained in:
Tim Mattox
2016-10-07 14:52:23 -04:00
parent e9fed80928
commit e27ed6c94a
23 changed files with 41546 additions and 80 deletions
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90
src/USER-DPD/fix_dpd_energy.cpp Normal file
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#include "stdio.h"
#include "string.h"
#include "fix_dpd_energy.h"
#include "atom.h"
#include "force.h"
#include "update.h"
#include "respa.h"
#include "modify.h"
#include "error.h"
#include "pair_dpd_fdt_energy.h"
using namespace LAMMPS_NS;
using namespace FixConst;
/* ---------------------------------------------------------------------- */
FixDPDenergy::FixDPDenergy(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg != 3 ) error->all(FLERR,"Illegal fix dpd/energy command");
pairDPDE = NULL;
pairDPDE = (PairDPDfdtEnergy *) force->pair_match("dpd/fdt/energy",1);
if(pairDPDE == NULL)
error->all(FLERR,"Must use pair_style dpd/fdt/energy with fix dpd/energy");
if(!(atom->dpd_flag))
error->all(FLERR,"Must use atom_style dpd/fdt/energy with fix dpd/energy");
}
/* ---------------------------------------------------------------------- */
int FixDPDenergy::setmask()
{
int mask = 0;
mask |= INITIAL_INTEGRATE;
mask |= FINAL_INTEGRATE;
return mask;
}
/* ----------------------------------------------------------------------
allow for both per-type and per-atom mass
------------------------------------------------------------------------- */
void FixDPDenergy::initial_integrate(int vflag)
{
int nlocal = atom->nlocal;
if (igroup == atom->firstgroup) nlocal = atom->nfirst;
double *uCond = atom->uCond;
double *uMech = atom->uMech;
double *duCond = pairDPDE->duCond;
double *duMech = pairDPDE->duMech;
for (int i = 0; i < nlocal; i++){
uCond[i] += 0.5*update->dt*duCond[i];
uMech[i] += 0.5*update->dt*duMech[i];
}
}
/* ---------------------------------------------------------------------- */
void FixDPDenergy::final_integrate()
{
int nlocal = atom->nlocal;
if (igroup == atom->firstgroup) nlocal = atom->nfirst;
double *uCond = atom->uCond;
double *uMech = atom->uMech;
double *duCond = pairDPDE->duCond;
double *duMech = pairDPDE->duMech;
for (int i = 0; i < nlocal; i++){
uCond[i] += 0.5*update->dt*duCond[i];
uMech[i] += 0.5*update->dt*duMech[i];
}
}