Made two changes:

-recomputed up-to-date pressure tensor (fixes energy
conservation problem with aniso)
	-changed ndof for iso (fixes volume fluctuation problem with iso)
This commit is contained in:
Aidan Thompson 2018-12-12 17:31:42 -07:00
parent ad1b1897d8
commit 6f33ce9dba
3 changed files with 69 additions and 5 deletions

View File

@ -261,6 +261,60 @@ void ComputePressure::compute_vector()
}
}
/* ----------------------------------------------------------------------
compute pressure tensor
assume KE tensor has already been computed
------------------------------------------------------------------------- */
void ComputePressure::compute_vector_ke_scalar()
{
invoked_vector = update->ntimestep;
if (update->vflag_global != invoked_vector)
error->all(FLERR,"Virial was not tallied on needed timestep");
if (force->kspace && kspace_virial && force->kspace->scalar_pressure_flag)
error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' for "
"tensor components with kspace_style msm");
// invoke temperature if it hasn't been already
double t;
if (keflag) {
if (temperature->invoked_scalar != update->ntimestep)
t = temperature->compute_scalar();
else t = temperature->scalar;
}
if (dimension == 3) {
inv_volume = 1.0 / (domain->xprd * domain->yprd * domain->zprd);
virial_compute(6,3);
if (keflag) {
double kescalar = temperature->dof * boltz * t / 3.0;
for (int i = 0; i < 3; i++)
vector[i] = (kescalar + virial[i]) * inv_volume * nktv2p;
for (int i = 3; i < 6; i++)
vector[i] = virial[i] * inv_volume * nktv2p;
} else
for (int i = 0; i < 6; i++)
vector[i] = virial[i] * inv_volume * nktv2p;
} else {
inv_volume = 1.0 / (domain->xprd * domain->yprd);
virial_compute(4,2);
if (keflag) {
double kescalar = temperature->dof * boltz * t / 2.0;
vector[0] = (kescalar + virial[0]) * inv_volume * nktv2p;
vector[1] = (kescalar + virial[1]) * inv_volume * nktv2p;
vector[3] = virial[3] * inv_volume * nktv2p;
vector[2] = vector[4] = vector[5] = 0.0;
} else {
vector[0] = virial[0] * inv_volume * nktv2p;
vector[1] = virial[1] * inv_volume * nktv2p;
vector[3] = virial[3] * inv_volume * nktv2p;
vector[2] = vector[4] = vector[5] = 0.0;
}
}
}
/* ---------------------------------------------------------------------- */
void ComputePressure::virial_compute(int n, int ndiag)

View File

@ -31,6 +31,7 @@ class ComputePressure : public Compute {
virtual void init();
virtual double compute_scalar();
virtual void compute_vector();
void compute_vector_ke_scalar();
void reset_extra_compute_fix(const char *);
protected:

View File

@ -29,6 +29,7 @@
#include "modify.h"
#include "fix_deform.h"
#include "compute.h"
#include "compute_pressure.h"
#include "kspace.h"
#include "update.h"
#include "respa.h"
@ -777,7 +778,7 @@ void FixNH::setup(int /*vflag*/)
if (pstat_flag) {
if (pstyle == ISO) pressure->compute_scalar();
else pressure->compute_vector();
else ((ComputePressure *)pressure)->compute_vector_ke_scalar();
couple();
pressure->addstep(update->ntimestep+1);
}
@ -850,7 +851,7 @@ void FixNH::initial_integrate(int /*vflag*/)
pressure->compute_scalar();
} else {
temperature->compute_vector();
pressure->compute_vector();
((ComputePressure *)pressure)->compute_vector_ke_scalar();
}
couple();
pressure->addstep(update->ntimestep+1);
@ -904,9 +905,16 @@ void FixNH::final_integrate()
t_current = temperature->compute_scalar();
tdof = temperature->dof;
// need to recompute pressure to account for change in KE
// t_current is up-to-date, but compute_temperature is not
// compute appropriately coupled elements of mvv_current
if (pstat_flag) {
if (pstyle == ISO) pressure->compute_scalar();
else pressure->compute_vector();
else {
temperature->compute_vector();
((ComputePressure *)pressure)->compute_vector_ke_scalar();
}
couple();
pressure->addstep(update->ntimestep+1);
}
@ -957,7 +965,7 @@ void FixNH::initial_integrate_respa(int /*vflag*/, int ilevel, int /*iloop*/)
pressure->compute_scalar();
} else {
temperature->compute_vector();
pressure->compute_vector();
((ComputePressure *)pressure)->compute_vector_ke_scalar();
}
couple();
pressure->addstep(update->ntimestep+1);
@ -1871,7 +1879,8 @@ void FixNH::nhc_press_integrate()
}
}
lkt_press = pdof * kt;
if (pstyle == ISO) lkt_press = kt;
else lkt_press = pdof * kt;
etap_dotdot[0] = (kecurrent - lkt_press)/etap_mass[0];
double ncfac = 1.0/nc_pchain;