void Reset_Pressures( simulation_data *data )
{
data->flex_bar.P_scalar = 0;
rtensor_MakeZero( data->flex_bar.P );
data->iso_bar.P = 0;
rvec_MakeZero( data->int_press );
rvec_MakeZero( data->my_ext_press );
rvec_MakeZero( data->ext_press );
}
void Compute_Center_of_Mass( reax_system *system, simulation_data *data,
mpi_datatypes *mpi_data, MPI_Comm comm )
{
int i;
double m, det; //xx, xy, xz, yy, yz, zz;
double tmp_mat[6], tot_mat[6];
rvec my_xcm, my_vcm, my_amcm, my_avcm;
rvec tvec, diff;
rtensor mat, inv;
rvec_MakeZero( my_xcm ); // position of CoM
rvec_MakeZero( my_vcm ); // velocity of CoM
rvec_MakeZero( my_amcm ); // angular momentum of CoM
rvec_MakeZero( my_avcm ); // angular velocity of CoM
/* Compute the position, vel. and ang. momentum about the centre of mass */
for( i = 0; i < system->n; ++i ) {
m = system->reax_param.sbp[ system->my_atoms[i].type ].mass;
rvec_ScaledAdd( my_xcm, m, system->my_atoms[i].x );
rvec_ScaledAdd( my_vcm, m, system->my_atoms[i].v );
rvec_Cross( tvec, system->my_atoms[i].x, system->my_atoms[i].v );
rvec_ScaledAdd( my_amcm, m, tvec );
}
MPI_Allreduce( my_xcm, data->xcm, 3, MPI_DOUBLE, MPI_SUM, comm );
MPI_Allreduce( my_vcm, data->vcm, 3, MPI_DOUBLE, MPI_SUM, comm );
MPI_Allreduce( my_amcm, data->amcm, 3, MPI_DOUBLE, MPI_SUM, comm );
rvec_Scale( data->xcm, data->inv_M, data->xcm );
rvec_Scale( data->vcm, data->inv_M, data->vcm );
rvec_Cross( tvec, data->xcm, data->vcm );
rvec_ScaledAdd( data->amcm, -data->M, tvec );
data->etran_cm = 0.5 * data->M * rvec_Norm_Sqr( data->vcm );
/* Calculate and then invert the inertial tensor */
for( i = 0; i < 6; ++i )
tmp_mat[i] = 0;
//my_xx = my_xy = my_xz = my_yy = my_yz = my_zz = 0;
for( i = 0; i < system->n; ++i ){
m = system->reax_param.sbp[ system->my_atoms[i].type ].mass;
rvec_ScaledSum( diff, 1., system->my_atoms[i].x, -1., data->xcm );
tmp_mat[0]/*my_xx*/ += diff[0] * diff[0] * m;
tmp_mat[1]/*my_xy*/ += diff[0] * diff[1] * m;
tmp_mat[2]/*my_xz*/ += diff[0] * diff[2] * m;
tmp_mat[3]/*my_yy*/ += diff[1] * diff[1] * m;
tmp_mat[4]/*my_yz*/ += diff[1] * diff[2] * m;
tmp_mat[5]/*my_zz*/ += diff[2] * diff[2] * m;
}
MPI_Reduce( tmp_mat, tot_mat, 6, MPI_DOUBLE, MPI_SUM, MASTER_NODE, comm );
if( system->my_rank == MASTER_NODE ) {
mat[0][0] = tot_mat[3] + tot_mat[5]; // yy + zz;
mat[0][1] = mat[1][0] = -tot_mat[1]; // -xy;
mat[0][2] = mat[2][0] = -tot_mat[2]; // -xz;
mat[1][1] = tot_mat[0] + tot_mat[5]; // xx + zz;
mat[2][1] = mat[1][2] = -tot_mat[4]; // -yz;
mat[2][2] = tot_mat[0] + tot_mat[3]; // xx + yy;
/* invert the inertial tensor */
det = ( mat[0][0] * mat[1][1] * mat[2][2] +
mat[0][1] * mat[1][2] * mat[2][0] +
mat[0][2] * mat[1][0] * mat[2][1] ) -
( mat[0][0] * mat[1][2] * mat[2][1] +
mat[0][1] * mat[1][0] * mat[2][2] +
mat[0][2] * mat[1][1] * mat[2][0] );
inv[0][0] = mat[1][1] * mat[2][2] - mat[1][2] * mat[2][1];
inv[0][1] = mat[0][2] * mat[2][1] - mat[0][1] * mat[2][2];
inv[0][2] = mat[0][1] * mat[1][2] - mat[0][2] * mat[1][1];
inv[1][0] = mat[1][2] * mat[2][0] - mat[1][0] * mat[2][2];
inv[1][1] = mat[0][0] * mat[2][2] - mat[0][2] * mat[2][0];
inv[1][2] = mat[0][2] * mat[1][0] - mat[0][0] * mat[1][2];
inv[2][0] = mat[1][0] * mat[2][1] - mat[2][0] * mat[1][1];
inv[2][1] = mat[2][0] * mat[0][1] - mat[0][0] * mat[2][1];
inv[2][2] = mat[0][0] * mat[1][1] - mat[1][0] * mat[0][1];
if( det > ALMOST_ZERO )
rtensor_Scale( inv, 1./det, inv );
else rtensor_MakeZero( inv );
/* Compute the angular velocity about the centre of mass */
rtensor_MatVec( data->avcm, inv, data->amcm );
}
MPI_Bcast( data->avcm, 3, MPI_DOUBLE, MASTER_NODE, comm );
/* Compute the rotational energy */
data->erot_cm = 0.5 * E_CONV * rvec_Dot( data->avcm, data->amcm );
}
