mirror of https://github.com/lammps/lammps.git
88 lines
2.2 KiB
C++
88 lines
2.2 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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www.cs.sandia.gov/~sjplimp/lammps.html
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Steve Plimpton, sjplimp@sandia.gov, Sandia National Laboratories
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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 "stdlib.h"
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#include "fix_com.h"
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#include "atom.h"
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#include "update.h"
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#include "domain.h"
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#include "group.h"
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#include "error.h"
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/* ---------------------------------------------------------------------- */
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FixCOM::FixCOM(int narg, char **arg) : Fix(narg, arg)
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{
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if (narg != 5) error->all("Illegal fix com command");
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nevery = atoi(arg[3]);
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if (nevery <= 0) error->all("Illegal fix com command");
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first = 1;
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MPI_Comm_rank(world,&me);
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if (me == 0) {
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fp = fopen(arg[4],"w");
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if (fp == NULL) {
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char str[128];
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sprintf(str,"Cannot open fix com file %s",arg[4]);
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error->one(str);
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}
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}
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if (me == 0) {
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fprintf(fp,"Center-of-mass for group %s\n",group->names[igroup]);
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fprintf(fp,"TimeStep x y z\n");
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}
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}
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/* ---------------------------------------------------------------------- */
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FixCOM::~FixCOM()
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{
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if (me == 0) fclose(fp);
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}
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/* ---------------------------------------------------------------------- */
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int FixCOM::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 FixCOM::init()
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{
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masstotal = group->mass(igroup);
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}
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/* ---------------------------------------------------------------------- */
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void FixCOM::setup()
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{
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if (first) end_of_step();
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first = 0;
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}
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/* ---------------------------------------------------------------------- */
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void FixCOM::end_of_step()
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{
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double xcm[3];
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group->xcm(igroup,masstotal,xcm);
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if (me == 0) fprintf(fp,"%d %g %g %g\n",
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update->ntimestep,xcm[0],xcm[1],xcm[2]);
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}
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