305 lines
8.3 KiB
C++
305 lines
8.3 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: Christina Payne (Vanderbilt U)
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------------------------------------------------------------------------- */
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#include "math.h"
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#include "string.h"
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#include "stdlib.h"
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#include "fix_efield.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 "force.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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using namespace LAMMPS_NS;
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using namespace FixConst;
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enum{CONSTANT,EQUAL,ATOM};
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/* ---------------------------------------------------------------------- */
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FixEfield::FixEfield(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(FLERR,"Illegal fix efield command");
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vector_flag = 1;
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scalar_flag = 1;
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size_vector = 3;
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global_freq = 1;
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extvector = 1;
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extscalar = 1;
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qe2f = force->qe2f;
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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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ex = qe2f * 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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ey = qe2f * 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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ez = qe2f * atof(arg[5]);
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zstyle = CONSTANT;
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}
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force_flag = 0;
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fsum[0] = fsum[1] = fsum[2] = fsum[3] = 0.0;
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maxatom = 0;
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efield = NULL;
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}
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/* ---------------------------------------------------------------------- */
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FixEfield::~FixEfield()
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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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memory->destroy(efield);
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}
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/* ---------------------------------------------------------------------- */
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int FixEfield::setmask()
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{
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int mask = 0;
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mask |= THERMO_ENERGY;
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mask |= POST_FORCE;
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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 FixEfield::init()
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{
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if (!atom->q_flag) error->all(FLERR,"Fix efield requires atom attribute q");
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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)
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error->all(FLERR,"Variable name for fix efield does not exist");
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if (input->variable->equalstyle(xvar)) xstyle = EQUAL;
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else if (input->variable->atomstyle(xvar)) xstyle = ATOM;
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else error->all(FLERR,"Variable for fix efield 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)
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error->all(FLERR,"Variable name for fix efield does not exist");
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if (input->variable->equalstyle(yvar)) ystyle = EQUAL;
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else if (input->variable->atomstyle(yvar)) ystyle = ATOM;
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else error->all(FLERR,"Variable for fix efield 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)
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error->all(FLERR,"Variable name for fix efield does not exist");
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if (input->variable->equalstyle(zvar)) zstyle = EQUAL;
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else if (input->variable->atomstyle(zvar)) zstyle = ATOM;
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else error->all(FLERR,"Variable for fix efield is invalid style");
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}
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if (xstyle == ATOM || ystyle == ATOM || zstyle == ATOM)
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varflag = ATOM;
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else 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 (strstr(update->integrate_style,"respa"))
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nlevels_respa = ((Respa *) update->integrate)->nlevels;
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}
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/* ---------------------------------------------------------------------- */
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void FixEfield::setup(int vflag)
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{
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if (strstr(update->integrate_style,"verlet"))
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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 FixEfield::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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apply F = qE
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------------------------------------------------------------------------- */
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void FixEfield::post_force(int vflag)
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{
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double **f = atom->f;
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double *q = atom->q;
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int *mask = atom->mask;
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int nlocal = atom->nlocal;
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// reallocate efield array if necessary
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if (varflag == ATOM && nlocal > maxatom) {
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maxatom = atom->nmax;
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memory->destroy(efield);
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memory->create(efield,maxatom,3,"efield:efield");
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}
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// fsum[0] = "potential energy" for added force
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// fsum[123] = extra force added to atoms
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fsum[0] = fsum[1] = fsum[2] = fsum[3] = 0.0;
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force_flag = 0;
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double **x = atom->x;
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double fx,fy,fz;
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if (varflag == CONSTANT) {
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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fx = q[i]*ex;
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fy = q[i]*ey;
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fz = q[i]*ez;
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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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fsum[0] -= fx*x[i][0]+fy*x[i][1]+fz*x[i][2];
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fsum[1] += fx;
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fsum[2] += fy;
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fsum[3] += fz;
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}
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// variable efield, wrap with clear/add
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} else {
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modify->clearstep_compute();
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if (xstyle == EQUAL) ex = qe2f * input->variable->compute_equal(xvar);
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else if (xstyle == ATOM && efield)
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input->variable->compute_atom(xvar,igroup,&efield[0][0],3,0);
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if (ystyle == EQUAL) ey = qe2f * input->variable->compute_equal(yvar);
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else if (ystyle == ATOM && efield)
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input->variable->compute_atom(yvar,igroup,&efield[0][1],3,0);
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if (zstyle == EQUAL) ez = qe2f * input->variable->compute_equal(zvar);
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else if (zstyle == ATOM && efield)
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input->variable->compute_atom(zvar,igroup,&efield[0][2],3,0);
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modify->addstep_compute(update->ntimestep + 1);
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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if (xstyle == ATOM) fx = qe2f * q[i]*efield[i][0];
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else fx = q[i]*ex;
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f[i][0] += fx;
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fsum[1] += fx;
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if (ystyle == ATOM) fy = qe2f * q[i]*efield[i][1];
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else fy = q[i]*ey;
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f[i][1] += fy;
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fsum[2] += fy;
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if (zstyle == ATOM) fz = qe2f * q[i]*efield[i][2];
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else fz = q[i]*ez;
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f[i][2] += fz;
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fsum[3] += fz;
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fsum[0] -= fx*x[i][0]+fy*x[i][1]+fz*x[i][2];
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}
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixEfield::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 FixEfield::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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memory usage of local atom-based array
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------------------------------------------------------------------------- */
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double FixEfield::memory_usage()
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{
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double bytes = 0.0;
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if (varflag == ATOM) bytes = atom->nmax*3 * sizeof(double);
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return bytes;
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}
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/* ----------------------------------------------------------------------
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return energy added by fix
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------------------------------------------------------------------------- */
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double FixEfield::compute_scalar(void)
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{
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if (force_flag == 0) {
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MPI_Allreduce(fsum,fsum_all,4,MPI_DOUBLE,MPI_SUM,world);
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force_flag = 1;
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}
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return fsum_all[0];
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}
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/* ----------------------------------------------------------------------
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return total extra force due to fix
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------------------------------------------------------------------------- */
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double FixEfield::compute_vector(int n)
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{
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if (force_flag == 0) {
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MPI_Allreduce(fsum,fsum_all,4,MPI_DOUBLE,MPI_SUM,world);
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force_flag = 1;
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}
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return fsum_all[n+1];
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}
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