forked from lijiext/lammps
138 lines
4.3 KiB
C++
138 lines
4.3 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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#include "math.h"
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#include "stdio.h"
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#include "string.h"
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#include "fix_nve_sphere_omp.h"
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#include "atom.h"
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#include "atom_vec.h"
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#include "update.h"
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#include "respa.h"
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#include "force.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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#define INERTIA 0.4 // moment of inertia prefactor for sphere
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enum{NONE,DIPOLE};
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/* ---------------------------------------------------------------------- */
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/* ---------------------------------------------------------------------- */
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void FixNVESphereOMP::initial_integrate(int vflag)
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{
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double * const * const x = atom->x;
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double * const * const v = atom->v;
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const double * const * const f = atom->f;
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double * const * const omega = atom->omega;
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const double * const * const torque = atom->torque;
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const double * const radius = atom->radius;
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const double * const rmass = atom->rmass;
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const int * const mask = atom->mask;
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const int nlocal = (igroup == atom->firstgroup) ? atom->nfirst : atom->nlocal;
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int i;
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// set timestep here since dt may have changed or come via rRESPA
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const double dtfrotate = dtf / INERTIA;
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// update v,x,omega for all particles
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// d_omega/dt = torque / inertia
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#if defined(_OPENMP)
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#pragma omp parallel for private(i) default(none)
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#endif
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for (i = 0; i < nlocal; i++) {
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if (mask[i] & groupbit) {
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const double 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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const double dtirotate = dtfrotate / (radius[i]*radius[i]*rmass[i]);
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omega[i][0] += dtirotate * torque[i][0];
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omega[i][1] += dtirotate * torque[i][1];
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omega[i][2] += dtirotate * torque[i][2];
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}
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}
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// update mu for dipoles
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// d_mu/dt = omega cross mu
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// renormalize mu to dipole length
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if (extra == DIPOLE) {
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double * const * const mu = atom->mu;
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#if defined(_OPENMP)
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#pragma omp parallel for private(i) default(none)
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#endif
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for (i = 0; i < nlocal; i++) {
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double g0,g1,g2,msq,scale;
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if (mask[i] & groupbit) {
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if (mu[i][3] > 0.0) {
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g0 = mu[i][0] + dtv * (omega[i][1]*mu[i][2]-omega[i][2]*mu[i][1]);
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g1 = mu[i][1] + dtv * (omega[i][2]*mu[i][0]-omega[i][0]*mu[i][2]);
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g2 = mu[i][2] + dtv * (omega[i][0]*mu[i][1]-omega[i][1]*mu[i][0]);
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msq = g0*g0 + g1*g1 + g2*g2;
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scale = mu[i][3]/sqrt(msq);
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mu[i][0] = g0*scale;
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mu[i][1] = g1*scale;
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mu[i][2] = g2*scale;
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}
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}
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}
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixNVESphereOMP::final_integrate()
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{
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double * const * const v = atom->v;
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const double * const * const f = atom->f;
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double * const * const omega = atom->omega;
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const double * const * const torque = atom->torque;
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const double * const rmass = atom->rmass;
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const double * const radius = atom->radius;
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const int * const mask = atom->mask;
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const int nlocal = (igroup == atom->firstgroup) ? atom->nfirst : atom->nlocal;
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int i;
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// set timestep here since dt may have changed or come via rRESPA
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const double dtfrotate = dtf / INERTIA;
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// update v,omega for all particles
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// d_omega/dt = torque / inertia
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#if defined(_OPENMP)
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#pragma omp parallel for private(i) default(none)
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#endif
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for (i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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const double 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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const double dtirotate = dtfrotate / (radius[i]*radius[i]*rmass[i]);
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omega[i][0] += dtirotate * torque[i][0];
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omega[i][1] += dtirotate * torque[i][1];
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omega[i][2] += dtirotate * torque[i][2];
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}
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}
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