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Added the option zero yes/no

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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@5857 f3b2605a-c512-4ea7-a41b-209d697bcdaa
This commit is contained in:
athomps
2011-03-27 23:34:04 +00:00
parent 7036f17032
commit fae9ea3b79
2 changed files with 78 additions and 13 deletions
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89
src/fix_langevin.cpp
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@ -32,6 +32,7 @@
#include "random_mars.h"
#include "memory.h"
#include "error.h"
#include "group.h"
using namespace LAMMPS_NS;
@ -71,6 +72,7 @@ FixLangevin::FixLangevin(LAMMPS *lmp, int narg, char **arg) :
for (int i = 1; i <= atom->ntypes; i++) ratio[i] = 1.0;
tally = 0;
zerosum = 0;
int iarg = 7;
while (iarg < narg) {
@ -88,6 +90,12 @@ FixLangevin::FixLangevin(LAMMPS *lmp, int narg, char **arg) :
else if (strcmp(arg[iarg+1],"yes") == 0) tally = 1;
else error->all("Illegal fix langevin command");
iarg += 2;
} else if (strcmp(arg[iarg],"zerosum") == 0) {
if (iarg+2 > narg) error->all("Illegal fix langevin command");
if (strcmp(arg[iarg+1],"no") == 0) zerosum = 0;
else if (strcmp(arg[iarg+1],"yes") == 0) zerosum = 1;
else error->all("Illegal fix langevin command");
iarg += 2;
} else error->all("Illegal fix langevin command");
}
@ -204,7 +212,20 @@ void FixLangevin::post_force_no_tally()
// computed on current nlocal atoms to remove bias
// test v = 0 since some computes mask non-participating atoms via v = 0
// and added force has extra term not multiplied by v = 0
// for ZEROSUM:
// Sum random force over all atoms in group
// Subtract sum/count from each atom in group
double fran[3],fsum[3],fsumall[3];
fsum[0] = fsum[1] = fsum[2] = 0.0;
bigint count;
if (zerosum) {
count = group->count(igroup);
if (count == 0)
error->all("Cannot zero Langevin force of 0 atoms");
}
if (rmass) {
double boltz = force->boltz;
double dt = update->dt;
@ -218,9 +239,15 @@ void FixLangevin::post_force_no_tally()
gamma2 = sqrt(rmass[i]) * sqrt(24.0*boltz/t_period/dt/mvv2e) / ftm2v;
gamma1 *= 1.0/ratio[type[i]];
gamma2 *= 1.0/sqrt(ratio[type[i]]) * tsqrt;
f[i][0] += gamma1*v[i][0] + gamma2*(random->uniform()-0.5);
f[i][1] += gamma1*v[i][1] + gamma2*(random->uniform()-0.5);
f[i][2] += gamma1*v[i][2] + gamma2*(random->uniform()-0.5);
fran[0] = gamma2*(random->uniform()-0.5);
fran[1] = gamma2*(random->uniform()-0.5);
fran[2] = gamma2*(random->uniform()-0.5);
f[i][0] += gamma1*v[i][0] + fran[0];
f[i][1] += gamma1*v[i][1] + fran[1];
f[i][2] += gamma1*v[i][2] + fran[2];
fsum[0] += fran[0];
fsum[1] += fran[1];
fsum[2] += fran[2];
}
}
@ -233,27 +260,42 @@ void FixLangevin::post_force_no_tally()
gamma1 *= 1.0/ratio[type[i]];
gamma2 *= 1.0/sqrt(ratio[type[i]]) * tsqrt;
temperature->remove_bias(i,v[i]);
fran[0] = gamma2*(random->uniform()-0.5);
fran[1] = gamma2*(random->uniform()-0.5);
fran[2] = gamma2*(random->uniform()-0.5);
if (v[i][0] != 0.0)
f[i][0] += gamma1*v[i][0] + gamma2*(random->uniform()-0.5);
f[i][0] += gamma1*v[i][0] + fran[0];
if (v[i][1] != 0.0)
f[i][1] += gamma1*v[i][1] + gamma2*(random->uniform()-0.5);
f[i][1] += gamma1*v[i][1] + fran[1];
if (v[i][2] != 0.0)
f[i][2] += gamma1*v[i][2] + gamma2*(random->uniform()-0.5);
f[i][2] += gamma1*v[i][2] + fran[2];
fsum[0] += fran[0];
fsum[1] += fran[1];
fsum[2] += fran[2];
temperature->restore_bias(i,v[i]);
}
}
}
} else {
if (which == NOBIAS) {
for (int i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
gamma1 = gfactor1[type[i]];
gamma2 = gfactor2[type[i]] * tsqrt;
f[i][0] += gamma1*v[i][0] + gamma2*(random->uniform()-0.5);
f[i][1] += gamma1*v[i][1] + gamma2*(random->uniform()-0.5);
f[i][2] += gamma1*v[i][2] + gamma2*(random->uniform()-0.5);
fran[0] = gamma2*(random->uniform()-0.5);
fran[1] = gamma2*(random->uniform()-0.5);
fran[2] = gamma2*(random->uniform()-0.5);
f[i][0] += gamma1*v[i][0] + fran[0];
f[i][1] += gamma1*v[i][1] + fran[1];
f[i][2] += gamma1*v[i][2] + fran[2];
fsum[0] += fran[0];
fsum[1] += fran[1];
fsum[2] += fran[2];
}
}
} else if (which == BIAS) {
@ -263,17 +305,40 @@ void FixLangevin::post_force_no_tally()
gamma1 = gfactor1[type[i]];
gamma2 = gfactor2[type[i]] * tsqrt;
temperature->remove_bias(i,v[i]);
fran[0] = gamma2*(random->uniform()-0.5);
fran[1] = gamma2*(random->uniform()-0.5);
fran[2] = gamma2*(random->uniform()-0.5);
if (v[i][0] != 0.0)
f[i][0] += gamma1*v[i][0] + gamma2*(random->uniform()-0.5);
f[i][0] += gamma1*v[i][0] + fran[0];
if (v[i][1] != 0.0)
f[i][1] += gamma1*v[i][1] + gamma2*(random->uniform()-0.5);
f[i][1] += gamma1*v[i][1] + fran[1];
if (v[i][2] != 0.0)
f[i][2] += gamma1*v[i][2] + gamma2*(random->uniform()-0.5);
f[i][2] += gamma1*v[i][2] + fran[2];
fsum[0] += fran[0];
fsum[1] += fran[1];
fsum[2] += fran[2];
temperature->restore_bias(i,v[i]);
}
}
}
}
// Set total force to zero
if (zerosum) {
MPI_Allreduce(fsum,fsumall,3,MPI_DOUBLE,MPI_SUM,world);
fsumall[0] /= count;
fsumall[1] /= count;
fsumall[2] /= count;
for (int i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
f[i][0] -= fsumall[0];
f[i][1] -= fsumall[1];
f[i][2] -= fsumall[2];
}
}
}
}
/* ---------------------------------------------------------------------- */