git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@6630 f3b2605a-c512-4ea7-a41b-209d697bcdaa
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sjplimp
292
src/USER-MISC/fix_addtorque.cpp
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292
src/USER-MISC/fix_addtorque.cpp
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/* ----------------------------------------------------------------------
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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: Laurent Joly (U Lyon, France)
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------------------------------------------------------------------------- */
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#include "string.h"
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#include "stdlib.h"
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#include "fix_addtorque.h"
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#include "atom.h"
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#include "update.h"
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#include "modify.h"
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#include "domain.h"
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#include "respa.h"
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#include "input.h"
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#include "variable.h"
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#include "memory.h"
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#include "error.h"
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#include "group.h"
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#include "force.h"
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using namespace LAMMPS_NS;
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enum{NONE,CONSTANT,EQUAL,ATOM};
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/* ---------------------------------------------------------------------- */
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FixAddTorque::FixAddTorque(LAMMPS *lmp, int narg, char **arg) :
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Fix(lmp, narg, arg)
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{
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if (narg != 6) error->all("Illegal fix addtorque command");
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scalar_flag = 1;
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vector_flag = 1;
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size_vector = 3;
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global_freq = 1;
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extscalar = 1;
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extvector = 1;
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xstr = ystr = zstr = NULL;
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if (strstr(arg[3],"v_") == arg[3]) {
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int n = strlen(&arg[3][2]) + 1;
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xstr = new char[n];
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strcpy(xstr,&arg[3][2]);
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} else {
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xvalue = atof(arg[3]);
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xstyle = CONSTANT;
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}
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if (strstr(arg[4],"v_") == arg[4]) {
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int n = strlen(&arg[4][2]) + 1;
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ystr = new char[n];
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strcpy(ystr,&arg[4][2]);
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} else {
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yvalue = atof(arg[4]);
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ystyle = CONSTANT;
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}
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if (strstr(arg[5],"v_") == arg[5]) {
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int n = strlen(&arg[5][2]) + 1;
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zstr = new char[n];
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strcpy(zstr,&arg[5][2]);
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} else {
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zvalue = atof(arg[5]);
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zstyle = CONSTANT;
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}
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force_flag = 0;
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foriginal[0] = foriginal[1] = foriginal[2] = foriginal[3] = 0.0;
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}
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/* ---------------------------------------------------------------------- */
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FixAddTorque::~FixAddTorque()
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{
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delete [] xstr;
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delete [] ystr;
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delete [] zstr;
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}
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/* ---------------------------------------------------------------------- */
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int FixAddTorque::setmask()
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{
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int mask = 0;
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mask |= POST_FORCE;
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mask |= THERMO_ENERGY;
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mask |= POST_FORCE_RESPA;
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mask |= MIN_POST_FORCE;
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return mask;
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}
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/* ---------------------------------------------------------------------- */
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void FixAddTorque::init()
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{
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// check variables
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if (xstr) {
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xvar = input->variable->find(xstr);
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if (xvar < 0) error->all("Variable name for fix addtorque does not exist");
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if (input->variable->equalstyle(xvar)) xstyle = EQUAL;
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else error->all("Variable for fix addtorque is invalid style");
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}
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if (ystr) {
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yvar = input->variable->find(ystr);
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if (yvar < 0) error->all("Variable name for fix addtorque does not exist");
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if (input->variable->equalstyle(yvar)) ystyle = EQUAL;
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else error->all("Variable for fix addtorque is invalid style");
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}
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if (zstr) {
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zvar = input->variable->find(zstr);
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if (zvar < 0) error->all("Variable name for fix addtorque does not exist");
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if (input->variable->equalstyle(zvar)) zstyle = EQUAL;
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else error->all("Variable for fix addtorque is invalid style");
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}
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if (xstyle == EQUAL || ystyle == EQUAL || zstyle == EQUAL)
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varflag = EQUAL;
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else varflag = CONSTANT;
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if (strcmp(update->integrate_style,"respa") == 0)
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nlevels_respa = ((Respa *) update->integrate)->nlevels;
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}
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/* ---------------------------------------------------------------------- */
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void FixAddTorque::setup(int vflag)
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{
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if (strcmp(update->integrate_style,"verlet") == 0)
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post_force(vflag);
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else {
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((Respa *) update->integrate)->copy_flevel_f(nlevels_respa-1);
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post_force_respa(vflag,nlevels_respa-1,0);
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((Respa *) update->integrate)->copy_f_flevel(nlevels_respa-1);
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixAddTorque::min_setup(int vflag)
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{
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post_force(vflag);
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}
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/* ---------------------------------------------------------------------- */
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void FixAddTorque::post_force(int vflag)
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{
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double **x = atom->x;
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double **f = atom->f;
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int *mask = atom->mask;
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int *type = atom->type;
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int *image = atom->image;
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double *mass = atom->mass;
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double *rmass = atom->rmass;
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int nlocal = atom->nlocal;
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double mvv2e = force->mvv2e;
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int xbox,ybox,zbox;
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double dx,dy,dz,vx,vy,vz,fx,fy,fz,massone,omegadotr;
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double xprd = domain->xprd;
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double yprd = domain->yprd;
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double zprd = domain->zprd;
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double tcm[3],xcm[3],angmom[3],omega[3],itorque[3],domegadt[3],tlocal[3];
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double inertia[3][3];
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// foriginal[0] = "potential energy" for added force
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// foriginal[123] = torque on atoms before extra force added
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foriginal[0] = foriginal[1] = foriginal[2] = foriginal[3] = 0.0;
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force_flag = 0;
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if (varflag == EQUAL) {
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// variable torque, wrap with clear/add
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modify->clearstep_compute();
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if (xstyle == EQUAL) xvalue = input->variable->compute_equal(xvar);
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if (ystyle == EQUAL) yvalue = input->variable->compute_equal(yvar);
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if (zstyle == EQUAL) zvalue = input->variable->compute_equal(zvar);
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modify->addstep_compute(update->ntimestep + 1);
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}
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atom->check_mass();
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double masstotal = group->mass(igroup);
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group->xcm(igroup,masstotal,xcm);
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group->inertia(igroup,xcm,inertia);
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group->angmom(igroup,xcm,angmom);
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group->omega(angmom,inertia,omega);
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tlocal[0] = tlocal[1] = tlocal[2] = 0.0;
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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xbox = (image[i] & 1023) - 512;
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ybox = (image[i] >> 10 & 1023) - 512;
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zbox = (image[i] >> 20) - 512;
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dx = (x[i][0] + xbox*xprd) - xcm[0];
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dy = (x[i][1] + ybox*yprd) - xcm[1];
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dz = (x[i][2] + zbox*zprd) - xcm[2];
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if (rmass) massone = rmass[i];
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else massone = mass[type[i]];
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omegadotr = omega[0]*dx+omega[1]*dy+omega[2]*dz;
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tlocal[0] += massone * omegadotr * (dy*omega[2] - dz*omega[1]);
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tlocal[1] += massone * omegadotr * (dz*omega[0] - dx*omega[2]);
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tlocal[2] += massone * omegadotr * (dx*omega[1] - dy*omega[0]);
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}
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MPI_Allreduce(tlocal,itorque,3,MPI_DOUBLE,MPI_SUM,world);
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tcm[0] = xvalue - mvv2e*itorque[0];
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tcm[1] = yvalue - mvv2e*itorque[1];
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tcm[2] = zvalue - mvv2e*itorque[2];
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group->omega(tcm,inertia,domegadt);
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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xbox = (image[i] & 1023) - 512;
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ybox = (image[i] >> 10 & 1023) - 512;
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zbox = (image[i] >> 20) - 512;
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dx = (x[i][0] + xbox*xprd) - xcm[0];
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dy = (x[i][1] + ybox*yprd) - xcm[1];
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dz = (x[i][2] + zbox*zprd) - xcm[2];
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vx = mvv2e*(dz*omega[1]-dy*omega[2]);
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vy = mvv2e*(dx*omega[2]-dz*omega[0]);
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vz = mvv2e*(dy*omega[0]-dx*omega[1]);
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if (rmass) massone = rmass[i];
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else massone = mass[type[i]];
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fx = massone * (dz*domegadt[1]-dy*domegadt[2] + vz*omega[1]-vy*omega[2]);
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fy = massone * (dx*domegadt[2]-dz*domegadt[0] + vx*omega[2]-vz*omega[0]);
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fz = massone * (dy*domegadt[0]-dx*domegadt[1] + vy*omega[0]-vx*omega[1]);
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// potential energy = - x dot f
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foriginal[0] -= fx*x[i][0] + fy*x[i][1] + fz*x[i][2];
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foriginal[1] += dy*f[i][2] - dz*f[i][1];
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foriginal[2] += dz*f[i][0] - dx*f[i][2];
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foriginal[3] += dx*f[i][1] - dy*f[i][0];
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f[i][0] += fx;
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f[i][1] += fy;
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f[i][2] += fz;
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixAddTorque::post_force_respa(int vflag, int ilevel, int iloop)
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{
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if (ilevel == nlevels_respa-1) post_force(vflag);
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}
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/* ---------------------------------------------------------------------- */
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void FixAddTorque::min_post_force(int vflag)
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{
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post_force(vflag);
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}
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/* ----------------------------------------------------------------------
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potential energy of added torque
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------------------------------------------------------------------------- */
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double FixAddTorque::compute_scalar()
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{
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// only sum across procs one time
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if (force_flag == 0) {
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MPI_Allreduce(foriginal,foriginal_all,4,MPI_DOUBLE,MPI_SUM,world);
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force_flag = 1;
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}
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return foriginal_all[0];
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}
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/* ----------------------------------------------------------------------
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return components of total torque on fix group before torque was changed
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------------------------------------------------------------------------- */
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double FixAddTorque::compute_vector(int n)
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{
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// only sum across procs one time
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if (force_flag == 0) {
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MPI_Allreduce(foriginal,foriginal_all,4,MPI_DOUBLE,MPI_SUM,world);
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force_flag = 1;
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}
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return foriginal_all[n+1];
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}
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