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fix_temp_rescale_cuda.cpp
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Tue, Apr 29, 09:11

fix_temp_rescale_cuda.cpp
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
Original Version:
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
See the README file in the top-level LAMMPS directory.
-----------------------------------------------------------------------
USER-CUDA Package and associated modifications:
https://sourceforge.net/projects/lammpscuda/
Christian Trott, christian.trott@tu-ilmenau.de
Lars Winterfeld, lars.winterfeld@tu-ilmenau.de
Theoretical Physics II, University of Technology Ilmenau, Germany
See the README file in the USER-CUDA directory.
This software is distributed under the GNU General Public License.
------------------------------------------------------------------------- */
#include <cstring>
#include <cstdlib>
#include <cmath>
#include "fix_temp_rescale_cuda.h"
#include "fix_temp_rescale_cuda_cu.h"
#include "atom.h"
#include "force.h"
#include "group.h"
#include "update.h"
#include "domain.h"
#include "region.h"
#include "comm.h"
#include "modify.h"
#include "compute.h"
#include "error.h"
#include "cuda.h"
#include "cuda_modify_flags.h"
using namespace LAMMPS_NS;
enum{NOBIAS,BIAS};
/* ---------------------------------------------------------------------- */
FixTempRescaleCuda::FixTempRescaleCuda(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
cuda = lmp->cuda;
if(cuda == NULL)
error->all("You cannot use a /cuda class, without activating 'cuda' acceleration. Provide '-c on' as command-line argument to LAMMPS..");
if (narg < 8) error->all("Illegal fix temp/rescale/cuda command");
nevery = atoi(arg[3]);
if (nevery <= 0) error->all("Illegal fix temp/rescale/cuda command");
scalar_flag = 1;
global_freq = nevery;
extscalar = 1;
t_start = atof(arg[4]);
t_stop = atof(arg[5]);
t_window = atof(arg[6]);
fraction = atof(arg[7]);
// create a new compute temp
// id = fix-ID + temp, compute group = fix group
int n = strlen(id) + 6;
id_temp = new char[n];
strcpy(id_temp,id);
strcat(id_temp,"_temp");
char **newarg = new char*[6];
newarg[0] = id_temp;
newarg[1] = group->names[igroup];
newarg[2] = (char *) "temp/cuda";
modify->add_compute(3,newarg);
delete [] newarg;
tflag = 1;
energy = 0.0;
}
/* ---------------------------------------------------------------------- */
FixTempRescaleCuda::~FixTempRescaleCuda()
{
// delete temperature if fix created it
if (tflag) modify->delete_compute(id_temp);
delete [] id_temp;
}
/* ---------------------------------------------------------------------- */
int FixTempRescaleCuda::setmask()
{
int mask = 0;
mask |= END_OF_STEP_CUDA;
mask |= THERMO_ENERGY_CUDA;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixTempRescaleCuda::init()
{
int icompute = modify->find_compute(id_temp);
if (icompute < 0)
error->all("Temperature ID for fix temp/rescale/cuda does not exist");
temperature = modify->compute[icompute];
if(not temperature->cudable)
error->warning("Fix temp/rescale/cuda uses non cudable temperature compute");
if (temperature->tempbias) which = BIAS;
else which = NOBIAS;
}
/* ---------------------------------------------------------------------- */
void FixTempRescaleCuda::end_of_step()
{
double t_current;
if(not temperature->cudable) {cuda->cu_x->download();cuda->cu_v->download();}
t_current = temperature->compute_scalar();
if (t_current == 0.0)
error->all("Computed temperature for fix temp/rescale/cuda cannot be 0.0");
double delta = update->ntimestep - update->beginstep;
delta /= update->endstep - update->beginstep;
double t_target = t_start + delta * (t_stop-t_start);
// rescale velocity of appropriate atoms if outside window
if (fabs(t_current-t_target) > t_window) {
t_target = t_current - fraction*(t_current-t_target);
double factor = sqrt(t_target/t_current);
double efactor = 0.5 * force->boltz * temperature->dof;
double **v = atom->v;
int *mask = atom->mask;
int nlocal = atom->nlocal;
if (which == NOBIAS) {
energy += (t_current-t_target) * efactor;
Cuda_FixTempRescaleCuda_EndOfStep(&cuda->shared_data, groupbit,factor);
} else if (which == BIAS) {
energy += (t_current-t_target) * efactor;
if(not temperature->cudable)
{
cuda->cu_x->download();cuda->cu_v->download();
for (int i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
temperature->remove_bias(i,v[i]);
v[i][0] *= factor;
v[i][1] *= factor;
v[i][2] *= factor;
temperature->restore_bias(i,v[i]);
}
}
cuda->cu_v->upload();
}
else
{
temperature->remove_bias_all();
Cuda_FixTempRescaleCuda_EndOfStep(&cuda->shared_data, groupbit,factor);
temperature->restore_bias_all();
}
}
}
}
/* ---------------------------------------------------------------------- */
int FixTempRescaleCuda::modify_param(int narg, char **arg)
{
if (strcmp(arg[0],"temp") == 0) {
if (narg < 2) error->all("Illegal fix_modify command");
if (tflag) {
modify->delete_compute(id_temp);
tflag = 0;
}
delete [] id_temp;
int n = strlen(arg[1]) + 1;
id_temp = new char[n];
strcpy(id_temp,arg[1]);
int icompute = modify->find_compute(id_temp);
if (icompute < 0) error->all("Could not find fix_modify temperature ID");
temperature = modify->compute[icompute];
if (temperature->tempflag == 0)
error->all("Fix_modify temperature ID does not compute temperature");
if (temperature->igroup != igroup && comm->me == 0)
error->warning("Group for fix_modify temp != fix group");
if(not temperature->cudable)
error->warning("Fix temp/rescale/cuda uses non cudable temperature compute");
return 2;
}
return 0;
}
/* ---------------------------------------------------------------------- */
void FixTempRescaleCuda::reset_target(double t_new)
{
t_start = t_stop = t_new;
}
/* ---------------------------------------------------------------------- */
double FixTempRescaleCuda::compute_scalar()
{
return energy;
}

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