void Compute_Pressure(reax_system* system, control_params *control,
simulation_data* data, mpi_datatypes *mpi_data)
{
int i;
reax_atom *p_atom;
rvec tmp, tx, int_press;
simulation_box *big_box = &(system->big_box);
/* Calculate internal pressure */
rvec_MakeZero( int_press );
// 0: both int and ext, 1: ext only, 2: int only
if( control->press_mode == 0 || control->press_mode == 2 ) {
for( i = 0; i < system->n; ++i ) {
p_atom = &( system->my_atoms[i] );
/* transform x into unitbox coordinates */
Transform_to_UnitBox( p_atom->x, big_box, 1, tx );
/* this atom's contribution to internal pressure */
rvec_Multiply( tmp, p_atom->f, tx );
rvec_Add( int_press, tmp );
}
}
/* sum up internal and external pressure */
MPI_Allreduce( int_press, data->int_press,
3, MPI_DOUBLE, MPI_SUM, mpi_data->comm_mesh3D );
MPI_Allreduce( data->my_ext_press, data->ext_press,
3, MPI_DOUBLE, MPI_SUM, mpi_data->comm_mesh3D );
/* kinetic contribution */
data->kin_press = 2.*(E_CONV*data->sys_en.e_kin) / (3.*big_box->V*P_CONV);
/* Calculate total pressure in each direction */
data->tot_press[0] = data->kin_press -
(( data->int_press[0] + data->ext_press[0] ) /
( big_box->box_norms[1] * big_box->box_norms[2] * P_CONV ));
data->tot_press[1] = data->kin_press -
(( data->int_press[1] + data->ext_press[1] ) /
( big_box->box_norms[0] * big_box->box_norms[2] * P_CONV ));
data->tot_press[2] = data->kin_press -
(( data->int_press[2] + data->ext_press[2] ) /
( big_box->box_norms[0] * big_box->box_norms[1] * P_CONV ));
data->iso_bar.P =
( data->tot_press[0] + data->tot_press[1] + data->tot_press[2] ) / 3.;
}
/* IMPORTANT: This function assumes that current kinetic energy
* the system is already computed
*
* IMPORTANT: In Klein's paper, it is stated that a dU/dV term needs
* to be added when there are long-range interactions or long-range
* corrections to short-range interactions present.
* We may want to add that for more accuracy.
*/
void Compute_Pressure(reax_system* system, control_params *control,
simulation_data* data, mpi_datatypes *mpi_data)
{
int i;
reax_atom *p_atom;
rvec tmp, tx, int_press;
simulation_box *big_box = &(system->big_box);
/* Calculate internal pressure */
rvec_MakeZero( int_press );
// 0: both int and ext, 1: ext only, 2: int only
if( control->press_mode == 0 || control->press_mode == 2 ) {
for( i = 0; i < system->n; ++i ) {
p_atom = &( system->my_atoms[i] );
/* transform x into unitbox coordinates */
Transform_to_UnitBox( p_atom->x, big_box, 1, tx );
/* this atom's contribution to internal pressure */
rvec_Multiply( tmp, p_atom->f, tx );
rvec_Add( int_press, tmp );
#if defined(DEBUG)
fprintf( stderr, "%8d%8.2f%8.2f%8.2f",
i+1, p_atom->x[0], p_atom->x[1], p_atom->x[2] );
fprintf( stderr, "%8.2f%8.2f%8.2f",
p_atom->f[0], p_atom->f[1], p_atom->f[2] );
fprintf( stderr, "%8.2f%8.2f%8.2f\n",
int_press[0], int_press[1], int_press[2] );
#endif
}
}
/* sum up internal and external pressure */
#if defined(DEBUG)
fprintf(stderr,"p%d:p_int(%10.5f %10.5f %10.5f)p_ext(%10.5f %10.5f %10.5f)\n",
system->my_rank, int_press[0], int_press[1], int_press[2],
data->my_ext_press[0], data->my_ext_press[1], data->my_ext_press[2] );
#endif
MPI_Allreduce( int_press, data->int_press,
3, MPI_DOUBLE, MPI_SUM, mpi_data->comm_mesh3D );
MPI_Allreduce( data->my_ext_press, data->ext_press,
3, MPI_DOUBLE, MPI_SUM, mpi_data->comm_mesh3D );
#if defined(DEBUG)
fprintf( stderr, "p%d: %10.5f %10.5f %10.5f\n",
system->my_rank,
data->int_press[0], data->int_press[1], data->int_press[2] );
fprintf( stderr, "p%d: %10.5f %10.5f %10.5f\n",
system->my_rank,
data->ext_press[0], data->ext_press[1], data->ext_press[2] );
#endif
/* kinetic contribution */
data->kin_press = 2.*(E_CONV*data->sys_en.e_kin) / (3.*big_box->V*P_CONV);
/* Calculate total pressure in each direction */
data->tot_press[0] = data->kin_press -
(( data->int_press[0] + data->ext_press[0] ) /
( big_box->box_norms[1] * big_box->box_norms[2] * P_CONV ));
data->tot_press[1] = data->kin_press -
(( data->int_press[1] + data->ext_press[1] ) /
( big_box->box_norms[0] * big_box->box_norms[2] * P_CONV ));
data->tot_press[2] = data->kin_press -
(( data->int_press[2] + data->ext_press[2] ) /
( big_box->box_norms[0] * big_box->box_norms[1] * P_CONV ));
/* Average pressure for the whole box */
data->iso_bar.P =
( data->tot_press[0] + data->tot_press[1] + data->tot_press[2] ) / 3.;
}