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fix_pimd.cpp
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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.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Package FixPIMD
Purpose Quantum Path Integral Algorithm for Quantum Chemistry
Copyright Voth Group @ University of Chicago
Authors Chris Knight & Yuxing Peng (yuxing at uchicago.edu)
Updated Oct-01-2011
Version 1.0
------------------------------------------------------------------------- */
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include "fix_pimd.h"
#include "universe.h"
#include "comm.h"
#include "force.h"
#include "atom.h"
#include "domain.h"
#include "update.h"
#include "memory.h"
#include "error.h"
using namespace LAMMPS_NS;
using namespace FixConst;
enum{PIMD,NMPIMD,CMD};
/* ---------------------------------------------------------------------- */
FixPIMD::FixPIMD(LAMMPS *lmp, int narg, char **arg) : Fix(lmp, narg, arg)
{
method = PIMD;
fmass = 1.0;
nhc_temp = 298.15;
nhc_nchain = 2;
sp = 1.0;
for(int i=3; i<narg-1; i+=2)
{
if(strcmp(arg[i],"method")==0)
{
if(strcmp(arg[i+1],"pimd")==0) method=PIMD;
else if(strcmp(arg[i+1],"nmpimd")==0) method=NMPIMD;
else if(strcmp(arg[i+1],"cmd")==0) method=CMD;
else error->universe_all(FLERR,"Unkown method parameter for fix pimd");
}
else if(strcmp(arg[i],"fmass")==0)
{
fmass = atof(arg[i+1]);
if(fmass<0.0 || fmass>1.0) error->universe_all(FLERR,"Invalid fmass value for fix pimd");
}
else if(strcmp(arg[i],"sp")==0)
{
sp = atof(arg[i+1]);
if(fmass<0.0) error->universe_all(FLERR,"Invalid sp value for fix pimd");
}
else if(strcmp(arg[i],"temp")==0)
{
nhc_temp = atof(arg[i+1]);
if(nhc_temp<0.0) error->universe_all(FLERR,"Invalid temp value for fix pimd");
}
else if(strcmp(arg[i],"nhc")==0)
{
nhc_nchain = atoi(arg[i+1]);
if(nhc_nchain<2) error->universe_all(FLERR,"Invalid nhc value for fix pimd");
}
else error->universe_all(arg[i],i+1,"Unkown keyword for fix pimd");
}
/* Initiation */
max_nsend = 0;
tag_send = NULL;
buf_send = NULL;
max_nlocal = 0;
buf_recv = NULL;
buf_beads = NULL;
size_plan = 0;
plan_send = plan_recv = NULL;
M_x2xp = M_xp2x = M_f2fp = M_fp2f = NULL;
lam = NULL;
mode_index = NULL;
mass = NULL;
array_atom = NULL;
nhc_eta = NULL;
nhc_eta_dot = NULL;
nhc_eta_dotdot = NULL;
nhc_eta_mass = NULL;
size_peratom_cols = 12 * nhc_nchain + 3;
nhc_offset_one_1 = 3 * nhc_nchain;
nhc_offset_one_2 = 3 * nhc_nchain +3;
nhc_size_one_1 = sizeof(double) * nhc_offset_one_1;
nhc_size_one_2 = sizeof(double) * nhc_offset_one_2;
restart_peratom = 1;
peratom_flag = 1;
peratom_freq = 1;
global_freq = 1;
thermo_energy = 1;
vector_flag = 1;
size_vector = 2;
extvector = 1;
comm_forward = 3;
atom->add_callback(0); // Call LAMMPS to allocate memory for per-atom array
atom->add_callback(1); // Call LAMMPS to re-assign restart-data for per-atom array
grow_arrays(atom->nmax);
// some initilizations
nhc_ready = false;
}
/* ---------------------------------------------------------------------- */
int FixPIMD::setmask()
{
int mask = 0;
mask |= POST_FORCE;
mask |= INITIAL_INTEGRATE;
mask |= FINAL_INTEGRATE;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixPIMD::init()
{
if (atom->map_style == 0)
error->all(FLERR,"Fix pimd requires an atom map, see atom_modify");
if(universe->me==0 && screen) fprintf(screen,"Fix pimd initializing Path-Integral ...\n");
// prepare the constants
np = universe->nworlds;
inverse_np = 1.0 / np;
/* The first solution for the force constant, using SI units
const double Boltzmann = 1.3806488E-23; // SI unit: J/K
const double Plank = 6.6260755E-34; // SI unit: m^2 kg / s
double hbar = Plank / ( 2.0 * M_PI ) * sp;
double beta = 1.0 / ( Boltzmann * input.nh_temp);
// - P / ( beta^2 * hbar^2) SI unit: s^-2
double _fbond = -1.0 / (beta*beta*hbar*hbar) * input.nbeads;
// convert the units: s^-2 -> (kcal/mol) / (g/mol) / (A^2)
fbond = _fbond * 4.184E+26;
*/
/* The current solution, using LAMMPS internal real units */
const double Boltzmann = force->boltz;
const double Plank = force->hplanck;
double hbar = Plank / ( 2.0 * M_PI );
double beta = 1.0 / (Boltzmann * nhc_temp);
double _fbond = 1.0 * np / (beta*beta*hbar*hbar) ;
omega_np = sqrt(np) / (hbar * beta) * sqrt(force->mvv2e);
fbond = - _fbond * force->mvv2e;
if(universe->me==0)
printf("Fix pimd -P/(beta^2 * hbar^2) = %20.7lE (kcal/mol/A^2)\n\n", fbond);
dtv = update->dt;
dtf = 0.5 * update->dt * force->ftm2v;
comm_init();
mass = new double [atom->ntypes+1];
if(method==CMD || method==NMPIMD) nmpimd_init();
else for(int i=1; i<=atom->ntypes; i++) mass[i] = atom->mass[i] / np * fmass;
if(!nhc_ready) nhc_init();
}
/* ---------------------------------------------------------------------- */
void FixPIMD::setup(int vflag)
{
if(universe->me==0 && screen) fprintf(screen,"Setting up Path-Integral ...\n");
post_force(vflag);
}
/* ---------------------------------------------------------------------- */
void FixPIMD::initial_integrate(int vflag)
{
nhc_update_v();
nhc_update_x();
}
/* ---------------------------------------------------------------------- */
void FixPIMD::final_integrate()
{
nhc_update_v();
}
/* ---------------------------------------------------------------------- */
void FixPIMD::post_force(int flag)
{
for(int i=0; i<atom->nlocal; i++) for(int j=0; j<3; j++) atom->f[i][j] /= np;
comm_exec(atom->x);
spring_force();
if(method==CMD || method==NMPIMD)
{
/* forward comm for the force on ghost atoms */
nmpimd_fill(atom->f);
/* inter-partition comm */
comm_exec(atom->f);
/* normal-mode transform */
nmpimd_transform(buf_beads, atom->f, M_f2fp[universe->iworld]);
}
}
/* ----------------------------------------------------------------------
Nose-Hoover Chains
------------------------------------------------------------------------- */
void FixPIMD::nhc_init()
{
double tau = 1.0 / omega_np;
double KT = force->boltz * nhc_temp;
double mass0 = KT * tau * tau;
int max = 3 * atom->nlocal;
for(int i=0; i<max; i++)
{
for(int ichain=0; ichain<nhc_nchain; ichain++)
{
nhc_eta[i][ichain] = 0.0;
nhc_eta_dot[i][ichain] = 0.0;
nhc_eta_dot[i][ichain] = 0.0;
nhc_eta_dotdot[i][ichain] = 0.0;
nhc_eta_mass[i][ichain] = mass0;
if((method==CMD || method==NMPIMD) && universe->iworld==0) ; else nhc_eta_mass[i][ichain] *= fmass;
}
nhc_eta_dot[i][nhc_nchain] = 0.0;
for(int ichain=1; ichain<nhc_nchain; ichain++)
nhc_eta_dotdot[i][ichain] = (nhc_eta_mass[i][ichain-1] * nhc_eta_dot[i][ichain-1]
* nhc_eta_dot[i][ichain-1] * force->mvv2e - KT) / nhc_eta_mass[i][ichain];
}
// Zero NH acceleration for CMD
if(method==CMD && universe->iworld==0) for(int i=0; i<max; i++)
for(int ichain=0; ichain<nhc_nchain; ichain++) nhc_eta_dotdot[i][ichain] = 0.0;
nhc_ready = true;
}
/* ---------------------------------------------------------------------- */
void FixPIMD::nhc_update_x()
{
int n = atom->nlocal;
double **x = atom->x;
double **v = atom->v;
if(method==CMD || method==NMPIMD)
{
nmpimd_fill(atom->v);
comm_exec(atom->v);
/* borrow the space of atom->f to store v in cartisian */
v = atom->f;
nmpimd_transform(buf_beads, v, M_xp2x[universe->iworld]);
}
for(int i=0; i<n; i++)
{
x[i][0] += dtv * v[i][0];
x[i][1] += dtv * v[i][1];
x[i][2] += dtv * v[i][2];
}
}
/* ---------------------------------------------------------------------- */
void FixPIMD::nhc_update_v()
{
int n = atom->nlocal;
int *type = atom->type;
double **v = atom->v;
double **f = atom->f;
for(int i=0; i<n; i++)
{
double dtfm = dtf / mass[type[i]];
v[i][0] += dtfm * f[i][0];
v[i][1] += dtfm * f[i][1];
v[i][2] += dtfm * f[i][2];
}
t_sys = 0.0;
if(method==CMD && universe->iworld==0) return;
double expfac;
int nmax = 3 * atom->nlocal;
double KT = force->boltz * nhc_temp;
double kecurrent, t_current;
double dthalf = 0.5 * update->dt;
double dt4 = 0.25 * update->dt;
double dt8 = 0.125 * update->dt;
for(int i=0; i<nmax; i++)
{
int iatm = i/3;
int idim = i%3;
double *vv = v[iatm];
kecurrent = mass[type[iatm]] * vv[idim]* vv[idim] * force->mvv2e;
t_current = kecurrent / force->boltz;
double *eta = nhc_eta[i];
double *eta_dot = nhc_eta_dot[i];
double *eta_dotdot = nhc_eta_dotdot[i];
eta_dotdot[0] = (kecurrent - KT) / nhc_eta_mass[i][0];
for(int ichain=nhc_nchain-1; ichain>0; ichain--)
{
expfac = exp(-dt8 * eta_dot[ichain+1]);
eta_dot[ichain] *= expfac;
eta_dot[ichain] += eta_dotdot[ichain] * dt4;
eta_dot[ichain] *= expfac;
}
expfac = exp(-dt8 * eta_dot[1]);
eta_dot[0] *= expfac;
eta_dot[0] += eta_dotdot[0] * dt4;
eta_dot[0] *= expfac;
// Update particle velocities half-step
double factor_eta = exp(-dthalf * eta_dot[0]);
vv[idim] *= factor_eta;
t_current *= (factor_eta * factor_eta);
kecurrent = force->boltz * t_current;
eta_dotdot[0] = (kecurrent - KT) / nhc_eta_mass[i][0];
for(int ichain=0; ichain<nhc_nchain; ichain++)
eta[ichain] += dthalf * eta_dot[ichain];
eta_dot[0] *= expfac;
eta_dot[0] += eta_dotdot[0] * dt4;
eta_dot[0] *= expfac;
for(int ichain=1; ichain<nhc_nchain; ichain++)
{
expfac = exp(-dt8 * eta_dot[ichain+1]);
eta_dot[ichain] *= expfac;
eta_dotdot[ichain] = (nhc_eta_mass[i][ichain-1] * eta_dot[ichain-1] * eta_dot[ichain-1]
- KT) / nhc_eta_mass[i][ichain];
eta_dot[ichain] += eta_dotdot[ichain] * dt4;
eta_dot[ichain] *= expfac;
}
t_sys += t_current;
}
t_sys /= nmax;
}
/* ----------------------------------------------------------------------
Normal Mode PIMD
------------------------------------------------------------------------- */
void FixPIMD::nmpimd_init()
{
memory->create(M_x2xp, np, np, "fix_feynman:M_x2xp");
memory->create(M_xp2x, np, np, "fix_feynman:M_xp2x");
memory->create(M_f2fp, np, np, "fix_feynman:M_f2fp");
memory->create(M_fp2f, np, np, "fix_feynman:M_fp2f");
lam = (double*) memory->smalloc(sizeof(double)*np, "FixPIMD::lam");
// Set up eigenvalues
lam[0] = 0.0;
if(np%2==0) lam[np-1] = 4.0 * np;
for(int i=2; i<=np/2; i++)
{
lam[2*i-3] = lam[2*i-2] = 2.0 * np * (1.0 - 1.0 *cos(2.0*M_PI*(i-1)/np));
}
// Set up eigenvectors for non-degenerated modes
for(int i=0; i<np; i++)
{
M_x2xp[0][i] = 1.0 / np;
if(np%2==0) M_x2xp[np-1][i] = 1.0 / np * pow(-1.0, i);
}
// Set up eigenvectors for degenerated modes
for(int i=0; i<(np-1)/2; i++) for(int j=0; j<np; j++)
{
M_x2xp[2*i+1][j] = sqrt(2.0) * cos ( 2.0 * M_PI * (i+1) * j / np) / np;
M_x2xp[2*i+2][j] = - sqrt(2.0) * sin ( 2.0 * M_PI * (i+1) * j / np) / np;
}
// Set up Ut
for(int i=0; i<np; i++)
for(int j=0; j<np; j++)
{
M_xp2x[i][j] = M_x2xp[j][i] * np;
M_f2fp[i][j] = M_x2xp[i][j] * np;
M_fp2f[i][j] = M_xp2x[i][j];
}
// Set up masses
int iworld = universe->iworld;
for(int i=1; i<=atom->ntypes; i++)
{
mass[i] = atom->mass[i];
if(iworld)
{
mass[i] *= lam[iworld];
mass[i] *= fmass;
}
}
}
/* ---------------------------------------------------------------------- */
void FixPIMD::nmpimd_fill(double **ptr)
{
comm_ptr = ptr;
comm->forward_comm_fix(this);
}
/* ---------------------------------------------------------------------- */
void FixPIMD::nmpimd_transform(double** src, double** des, double *vector)
{
int n = atom->nlocal;
int m = 0;
for(int i=0; i<n; i++) for(int d=0; d<3; d++)
{
des[i][d] = 0.0;
for(int j=0; j<np; j++) { des[i][d] += (src[j][m] * vector[j]); }
m++;
}
}
/* ---------------------------------------------------------------------- */
void FixPIMD::spring_force()
{
spring_energy = 0.0;
double **x = atom->x;
double **f = atom->f;
double* _mass = atom->mass;
int* type = atom->type;
int nlocal = atom->nlocal;
double* xlast = buf_beads[x_last];
double* xnext = buf_beads[x_next];
for(int i=0; i<nlocal; i++)
{
double delx1 = xlast[0] - x[i][0];
double dely1 = xlast[1] - x[i][1];
double delz1 = xlast[2] - x[i][2];
xlast += 3;
domain->minimum_image(delx1, dely1, delz1);
double delx2 = xnext[0] - x[i][0];
double dely2 = xnext[1] - x[i][1];
double delz2 = xnext[2] - x[i][2];
xnext += 3;
domain->minimum_image(delx2, dely2, delz2);
double ff = fbond * _mass[type[i]];
double dx = delx1+delx2;
double dy = dely1+dely2;
double dz = delz1+delz2;
f[i][0] -= (dx) * ff;
f[i][1] -= (dy) * ff;
f[i][2] -= (dz) * ff;
spring_energy += (dx*dx+dy*dy+dz*dz);
}
}
/* ----------------------------------------------------------------------
Comm operations
------------------------------------------------------------------------- */
void FixPIMD::comm_init()
{
if(size_plan)
{
delete [] plan_send;
delete [] plan_recv;
}
if(method == PIMD)
{
size_plan = 2;
plan_send = new int [2];
plan_recv = new int [2];
mode_index = new int [2];
int rank_last = universe->me - comm->nprocs;
int rank_next = universe->me + comm->nprocs;
if(rank_last<0) rank_last += universe->nprocs;
if(rank_next>=universe->nprocs) rank_next -= universe->nprocs;
plan_send[0] = rank_next; plan_send[1] = rank_last;
plan_recv[0] = rank_last; plan_recv[1] = rank_next;
mode_index[0] = 0; mode_index[1] = 1;
x_last = 1; x_next = 0;
}
else
{
size_plan = np - 1;
plan_send = new int [size_plan];
plan_recv = new int [size_plan];
mode_index = new int [size_plan];
for(int i=0; i<size_plan; i++)
{
plan_send[i] = universe->me + comm->nprocs * (i+1);
if(plan_send[i]>=universe->nprocs) plan_send[i] -= universe->nprocs;
plan_recv[i] = universe->me - comm->nprocs * (i+1);
if(plan_recv[i]<0) plan_recv[i] += universe->nprocs;
mode_index[i]=(universe->iworld+i+1)%(universe->nworlds);
}
x_next = (universe->iworld+1+universe->nworlds)%(universe->nworlds);
x_last = (universe->iworld-1+universe->nworlds)%(universe->nworlds);
}
if(buf_beads)
{
for(int i=0; i<np; i++) if(buf_beads[i]) delete [] buf_beads[i];
delete [] buf_beads;
}
buf_beads = new double* [np];
for(int i=0; i<np; i++) buf_beads[i] = NULL;
}
/* ---------------------------------------------------------------------- */
void FixPIMD::comm_exec(double **ptr)
{
int nlocal = atom->nlocal;
if(nlocal > max_nlocal)
{
max_nlocal = nlocal+200;
int size = sizeof(double) * max_nlocal * 3;
buf_recv = (double*) memory->srealloc(buf_recv, size, "FixPIMD:x_recv");
for(int i=0; i<np; i++)
buf_beads[i] = (double*) memory->srealloc(buf_beads[i], size, "FixPIMD:x_beads[i]");
}
// copy local positions
memcpy(buf_beads[universe->iworld], &(ptr[0][0]), sizeof(double)*nlocal*3);
// go over comm plans
for(int iplan = 0; iplan<size_plan; iplan++)
{
// sendrecv nlocal
int nsend;
MPI_Sendrecv( &(nlocal), 1, MPI_INT, plan_send[iplan], 0,
&(nsend), 1, MPI_INT, plan_recv[iplan], 0, universe->uworld, MPI_STATUS_IGNORE);
// allocate arrays
if(nsend > max_nsend)
{
max_nsend = nsend+200;
tag_send = (int*) memory->srealloc(tag_send, sizeof(int)*max_nsend, "FixPIMD:tag_send");
buf_send = (double*) memory->srealloc(buf_send, sizeof(double)*max_nsend*3, "FixPIMD:x_send");
}
// send tags
MPI_Sendrecv( atom->tag, nlocal, MPI_INT, plan_send[iplan], 0,
tag_send, nsend, MPI_INT, plan_recv[iplan], 0, universe->uworld, MPI_STATUS_IGNORE);
// wrap positions
double *wrap_ptr = buf_send;
int ncpy = sizeof(double)*3;
for(int i=0; i<nsend; i++)
{
int index = atom->map(tag_send[i]);
if(index<0)
{
char error_line[256];
sprintf(error_line, "Atom " TAGINT_FORMAT " is missing at world [%d] "
"rank [%d] required by rank [%d] (" TAGINT_FORMAT ", "
TAGINT_FORMAT ", " TAGINT_FORMAT ").\n",tag_send[i],
universe->iworld, comm->me, plan_recv[iplan],
atom->tag[0], atom->tag[1], atom->tag[2]);
error->universe_one(FLERR,error_line);
}
memcpy(wrap_ptr, ptr[index], ncpy);
wrap_ptr += 3;
}
// sendrecv x
MPI_Sendrecv( buf_send, nsend*3, MPI_DOUBLE, plan_recv[iplan], 0,
buf_recv, nlocal*3, MPI_DOUBLE, plan_send[iplan], 0, universe->uworld, MPI_STATUS_IGNORE);
// copy x
memcpy(buf_beads[mode_index[iplan]], buf_recv, sizeof(double)*nlocal*3);
}
}
/* ---------------------------------------------------------------------- */
int FixPIMD::pack_forward_comm(int n, int *list, double *buf,
int pbc_flag, int *pbc)
{
int i,j,m;
m = 0;
for (i = 0; i < n; i++) {
j = list[i];
buf[m++] = comm_ptr[j][0];
buf[m++] = comm_ptr[j][1];
buf[m++] = comm_ptr[j][2];
}
return m;
}
/* ---------------------------------------------------------------------- */
void FixPIMD::unpack_forward_comm(int n, int first, double *buf)
{
int i,m,last;
m = 0;
last = first + n;
for (i = first; i < last; i++) {
comm_ptr[i][0] = buf[m++];
comm_ptr[i][1] = buf[m++];
comm_ptr[i][2] = buf[m++];
}
}
/* ----------------------------------------------------------------------
Memory operations
------------------------------------------------------------------------- */
double FixPIMD::memory_usage()
{
double bytes = 0;
bytes = atom->nmax * size_peratom_cols * sizeof(double);
return bytes;
}
/* ---------------------------------------------------------------------- */
void FixPIMD::grow_arrays(int nmax)
{
if (nmax==0) return;
int count = nmax*3;
memory->grow(array_atom, nmax, size_peratom_cols, "FixPIMD::array_atom");
memory->grow(nhc_eta, count, nhc_nchain, "FixPIMD::nh_eta");
memory->grow(nhc_eta_dot, count, nhc_nchain+1, "FixPIMD::nh_eta_dot");
memory->grow(nhc_eta_dotdot, count, nhc_nchain, "FixPIMD::nh_eta_dotdot");
memory->grow(nhc_eta_mass, count, nhc_nchain, "FixPIMD::nh_eta_mass");
}
/* ---------------------------------------------------------------------- */
void FixPIMD::copy_arrays(int i, int j, int delflag)
{
int i_pos = i*3;
int j_pos = j*3;
memcpy(nhc_eta [j_pos], nhc_eta [i_pos], nhc_size_one_1);
memcpy(nhc_eta_dot [j_pos], nhc_eta_dot [i_pos], nhc_size_one_2);
memcpy(nhc_eta_dotdot[j_pos], nhc_eta_dotdot[i_pos], nhc_size_one_1);
memcpy(nhc_eta_mass [j_pos], nhc_eta_mass [i_pos], nhc_size_one_1);
}
/* ---------------------------------------------------------------------- */
int FixPIMD::pack_exchange(int i, double *buf)
{
int offset=0;
int pos = i * 3;
memcpy(buf+offset, nhc_eta[pos], nhc_size_one_1); offset += nhc_offset_one_1;
memcpy(buf+offset, nhc_eta_dot[pos], nhc_size_one_2); offset += nhc_offset_one_2;
memcpy(buf+offset, nhc_eta_dotdot[pos], nhc_size_one_1); offset += nhc_offset_one_1;
memcpy(buf+offset, nhc_eta_mass[pos], nhc_size_one_1); offset += nhc_offset_one_1;
return size_peratom_cols;
}
/* ---------------------------------------------------------------------- */
int FixPIMD::unpack_exchange(int nlocal, double *buf)
{
int offset=0;
int pos = nlocal*3;
memcpy(nhc_eta[pos], buf+offset, nhc_size_one_1); offset += nhc_offset_one_1;
memcpy(nhc_eta_dot[pos], buf+offset, nhc_size_one_2); offset += nhc_offset_one_2;
memcpy(nhc_eta_dotdot[pos], buf+offset, nhc_size_one_1); offset += nhc_offset_one_1;
memcpy(nhc_eta_mass[pos], buf+offset, nhc_size_one_1); offset += nhc_offset_one_1;
return size_peratom_cols;
}
/* ---------------------------------------------------------------------- */
int FixPIMD::pack_restart(int i, double *buf)
{
int offset=0;
int pos = i * 3;
buf[offset++] = size_peratom_cols+1;
memcpy(buf+offset, nhc_eta[pos], nhc_size_one_1); offset += nhc_offset_one_1;
memcpy(buf+offset, nhc_eta_dot[pos], nhc_size_one_2); offset += nhc_offset_one_2;
memcpy(buf+offset, nhc_eta_dotdot[pos], nhc_size_one_1); offset += nhc_offset_one_1;
memcpy(buf+offset, nhc_eta_mass[pos], nhc_size_one_1); offset += nhc_offset_one_1;
return size_peratom_cols+1;
}
/* ---------------------------------------------------------------------- */
void FixPIMD::unpack_restart(int nlocal, int nth)
{
double **extra = atom->extra;
// skip to Nth set of extra values
int m = 0;
for (int i=0; i<nth; i++) m += static_cast<int> (extra[nlocal][m]);
m++;
int pos = nlocal * 3;
memcpy(nhc_eta[pos], extra[nlocal]+m, nhc_size_one_1); m += nhc_offset_one_1;
memcpy(nhc_eta_dot[pos], extra[nlocal]+m, nhc_size_one_2); m += nhc_offset_one_2;
memcpy(nhc_eta_dotdot[pos], extra[nlocal]+m, nhc_size_one_1); m += nhc_offset_one_1;
memcpy(nhc_eta_mass[pos], extra[nlocal]+m, nhc_size_one_1); m += nhc_offset_one_1;
nhc_ready = true;
}
/* ---------------------------------------------------------------------- */
int FixPIMD::maxsize_restart()
{
return size_peratom_cols+1;
}
/* ---------------------------------------------------------------------- */
int FixPIMD::size_restart(int nlocal)
{
return size_peratom_cols+1;
}
/* ---------------------------------------------------------------------- */
double FixPIMD::compute_vector(int n)
{
if(n==0) { return spring_energy; }
if(n==1) { return t_sys; }
return 0.0;
}

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