git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@2727 f3b2605a-c512-4ea7-a41b-209d697bcdaa

This commit is contained in:
sjplimp 2009-04-06 15:59:15 +00:00
parent ea615ff444
commit 9a491edd03
3 changed files with 529 additions and 0 deletions

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src/fix_ttm.cpp Normal file
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#include "mpi.h"
#include "math.h"
#include "string.h"
#include "stdlib.h"
#include "fix_ttm.h"
#include "atom.h"
#include "force.h"
#include "update.h"
#include "domain.h"
#include "region.h"
#include "respa.h"
#include "comm.h"
#include "random_mars.h"
#include "memory.h"
#include "error.h"
#define MAX(A,B) ((A) > (B)) ? (A) : (B)
#define MAXLINE 1024
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
FixTTM::FixTTM(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg < 15) error->all("Illegal fix TTM command");
int seed = atoi(arg[3]);
electronic_specific_heat = atof(arg[4]);
electronic_density = atof(arg[5]);
electronic_thermal_conductivity = atof(arg[6]);
gamma_p = atof(arg[7]);
gamma_s = atof(arg[8]);
v_0 = atof(arg[9]);
nxnodes = atoi(arg[10]);
nynodes = atoi(arg[11]);
nznodes = atoi(arg[12]);
fpr = fopen(arg[13],"r");
if (fpr == NULL) {
char str[128];
sprintf(str,"Cannot open file %s",arg[13]);
error->one(str);
}
nfileevery = atoi(arg[14]);
if (nfileevery) {
if (narg != 16) error->all("Illegal fix ttm command");
MPI_Comm_rank(world,&me);
if (me == 0) {
fp = fopen(arg[15],"w");
if (fp == NULL) {
char str[128];
sprintf(str,"Cannot open fix ttm file %s",arg[15]);
error->one(str);
}
}
}
if (seed <= 0) error->all("Fix TTM seed must be >= 0");
if (electronic_specific_heat <= 0.0) error->all("Fix TTM electronic_specific_heat must be > 0.0");
if (electronic_density <= 0.0) error->all("Fix TTM electronic_density must be > 0.0");
if (electronic_thermal_conductivity < 0.0) error->all("Fix TTM electronic_thermal_conductivity must be >= 0.0");
if (gamma_p <= 0.0) error->all("Fix TTM gamma_p must be > 0.0");
if (gamma_s < 0.0) error->all("Fix TTM gamma_s must be >= 0.0");
if (v_0 < 0.0) error->all("Fix TTM v_0 must be >= 0.0");
v_0_sq = v_0*v_0;
if ((nxnodes <= 0) or (nynodes <= 0) or (nznodes <= 0)) error->all("Fix TTM nnodes must be > 0");
nsum = nsum_prime = nsum_all = nsum_prime_all = T_initial_set = NULL;
sum_vsq = sum_vsq_prime = sum_mass_vsq = sum_mass_vsq_prime = sum_vsq_all = sum_vsq_prime_all = NULL;
sum_mass_vsq_all = sum_mass_vsq_prime_all = T_electron_old = T_electron = T_a = T_a_prime = g_s = g_p = NULL;
// initialize Marsaglia RNG with processor-unique seed
random = new RanMars(lmp,seed + comm->me);
// allocate per-type arrays for force prefactors
gfactor1 = new double[atom->ntypes+1];
gfactor2 = new double[atom->ntypes+1];
total_nnodes = nxnodes*nynodes*nznodes;
}
/* ---------------------------------------------------------------------- */
FixTTM::~FixTTM()
{
if (nfileevery && me == 0) fclose(fp);
delete random;
delete [] gfactor1;
delete [] gfactor2;
memory->destroy_3d_int_array(nsum);
memory->destroy_3d_int_array(nsum_prime);
memory->destroy_3d_int_array(nsum_all);
memory->destroy_3d_int_array(nsum_prime_all);
memory->destroy_3d_int_array(T_initial_set);
memory->destroy_3d_double_array(sum_vsq);
memory->destroy_3d_double_array(sum_vsq_prime);
memory->destroy_3d_double_array(sum_mass_vsq);
memory->destroy_3d_double_array(sum_mass_vsq_prime);
memory->destroy_3d_double_array(sum_vsq_all);
memory->destroy_3d_double_array(sum_vsq_prime_all);
memory->destroy_3d_double_array(sum_mass_vsq_all);
memory->destroy_3d_double_array(sum_mass_vsq_prime_all);
memory->destroy_3d_double_array(T_electron_old);
memory->destroy_3d_double_array(T_electron);
memory->destroy_3d_double_array(T_a);
memory->destroy_3d_double_array(T_a_prime);
memory->destroy_3d_double_array(g_s);
memory->destroy_3d_double_array(g_p);
}
/* ---------------------------------------------------------------------- */
int FixTTM::setmask()
{
int mask = 0;
mask |= POST_FORCE;
mask |= POST_FORCE_RESPA;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixTTM::init()
{
if (atom->mass == NULL)
error->all("Cannot use fix TTM without per-type mass defined");
// set force prefactors
for (int i = 1; i <= atom->ntypes; i++) {
gfactor1[i] = - gamma_p / force->ftm2v;
gfactor2[i] = sqrt(24.0*force->boltz*gamma_p/update->dt/force->mvv2e) / force->ftm2v;
}
if (strcmp(update->integrate_style,"respa") == 0)
nlevels_respa = ((Respa *) update->integrate)->nlevels;
// allocate memory for 3d vectors
nsum = memory->create_3d_int_array(nxnodes,nynodes,nznodes,"TTM:nsum");
nsum_prime = memory->create_3d_int_array(nxnodes,nynodes,nznodes,"TTM:nsum_prime");
nsum_all = memory->create_3d_int_array(nxnodes,nynodes,nznodes,"TTM:nsum_all");
nsum_prime_all = memory->create_3d_int_array(nxnodes,nynodes,nznodes,"TTM:nsum_prime_all");
T_initial_set = memory->create_3d_int_array(nxnodes,nynodes,nznodes,"TTM:T_initial_set");
sum_vsq = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:sum_vsq");
sum_vsq_prime = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:sum_vsq_prime");
sum_mass_vsq = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:sum_mass_vsq");
sum_mass_vsq_prime = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:sum_mass_vsq_prime");
sum_vsq_all = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:sum_vsq_all");
sum_vsq_prime_all = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:sum_vsq_prime_all");
sum_mass_vsq_all = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:sum_mass_vsq_all");
sum_mass_vsq_prime_all = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:sum_mass_vsq_prime_all");
T_electron_old = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:T_electron_old");
T_electron = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:T_electron");
T_a = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:T_a");
T_a_prime = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:T_a_prime");
g_s = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:g_s");
g_p = memory->create_3d_double_array(nxnodes,nynodes,nznodes,"TTM:g_p");
// set initial electron temperatures from user-supplied file
if (me == 0) read_initial_electron_temperatures();
MPI_Bcast(&T_electron[0][0][0],total_nnodes,MPI_DOUBLE,0,world);
}
/* ----------------------------------------------------------------------
read in initial electron temperatures from a user-specified file
only called by proc 0
------------------------------------------------------------------------- */
void FixTTM::read_initial_electron_temperatures()
{
char line[MAXLINE];
for (int ixnode = 0; ixnode < nxnodes; ixnode++) {
for (int iynode = 0; iynode < nynodes; iynode++) {
for (int iznode = 0; iznode < nznodes; iznode++) {
T_initial_set[ixnode][iynode][iznode] = 0;
}
}
}
// read initial electron temperature values from file
int ixnode,iynode,iznode;
double T_tmp;
while (1) {
if (fgets(line,MAXLINE,fpr) == NULL) break;
sscanf(line,"%d %d %d %lg",&ixnode,&iynode,&iznode,&T_tmp);
if (T_tmp < 0.0) error->all("Fix TTM electron temperatures must be > 0.0");
T_electron[ixnode][iynode][iznode] = T_tmp;
T_initial_set[ixnode][iynode][iznode] = 1;
}
for (int ixnode = 0; ixnode < nxnodes; ixnode++) {
for (int iynode = 0; iynode < nynodes; iynode++) {
for (int iznode = 0; iznode < nznodes; iznode++) {
if (T_initial_set[ixnode][iynode][iznode] == 0)
error->all("All initial temperatures have not been set in the TTM fix.");
}
}
}
// close file
fclose(fpr);
}
/* ---------------------------------------------------------------------- */
void FixTTM::setup(int vflag)
{
if (strcmp(update->integrate_style,"verlet") == 0)
post_force(vflag);
else {
((Respa *) update->integrate)->copy_flevel_f(nlevels_respa-1);
post_force_respa(vflag,nlevels_respa-1,0);
((Respa *) update->integrate)->copy_f_flevel(nlevels_respa-1);
}
}
/* ---------------------------------------------------------------------- */
void FixTTM::post_force(int vflag)
{
update_electron_temperatures();
double **x = atom->x;
double **v = atom->v;
double **f = atom->f;
int *type = atom->type;
int *mask = atom->mask;
int nlocal = atom->nlocal;
double gamma1,gamma2;
// apply damping and thermostat to all atoms in fix group
for (int i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
double xscale = (x[i][0] - domain->boxlo[0])/domain->xprd;
double yscale = (x[i][1] - domain->boxlo[1])/domain->yprd;
double zscale = (x[i][2] - domain->boxlo[2])/domain->zprd;
int ixnode = static_cast<int>(xscale*nxnodes);
int iynode = static_cast<int>(yscale*nynodes);
int iznode = static_cast<int>(zscale*nznodes);
while (ixnode > nxnodes-1) ixnode -= nxnodes;
while (iynode > nynodes-1) iynode -= nynodes;
while (iznode > nznodes-1) iznode -= nznodes;
while (ixnode < 0) ixnode += nxnodes;
while (iynode < 0) iynode += nynodes;
while (iznode < 0) iznode += nznodes;
double tsqrt = sqrt(T_electron[ixnode][iynode][iznode]);
gamma1 = gfactor1[type[i]];
double vsq = v[i][0]*v[i][0] + v[i][1]*v[i][1] + v[i][2]*v[i][2];
if (vsq > v_0_sq) gamma1 *= (gamma_p + gamma_s)/gamma_p;
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);
}
}
}
/* ---------------------------------------------------------------------- */
void FixTTM::post_force_respa(int vflag, int ilevel, int iloop)
{
if (ilevel == nlevels_respa-1) post_force(vflag);
}
/* ---------------------------------------------------------------------- */
void FixTTM::reset_dt()
{
for (int i = 1; i <= atom->ntypes; i++) {
gfactor2[i] = sqrt(24.0*force->boltz*gamma_p/update->dt/force->mvv2e) / force->ftm2v;
}
}
/* ---------------------------------------------------------------------- */
void FixTTM::update_electron_temperatures()
{
double **x = atom->x;
double **v = atom->v;
int *type = atom->type;
int *mask = atom->mask;
int nlocal = atom->nlocal;
// compute atomic Ta, and Ta' (for high v atoms) for each node
for (int ixnode = 0; ixnode < nxnodes; ixnode++) {
for (int iynode = 0; iynode < nynodes; iynode++) {
for (int iznode = 0; iznode < nznodes; iznode++) {
nsum[ixnode][iynode][iznode] = 0;
nsum_prime[ixnode][iynode][iznode] = 0;
nsum_all[ixnode][iynode][iznode] = 0;
nsum_prime_all[ixnode][iynode][iznode] = 0;
sum_vsq[ixnode][iynode][iznode] = 0.0;
sum_vsq_prime[ixnode][iynode][iznode] = 0.0;
sum_mass_vsq[ixnode][iynode][iznode] = 0.0;
sum_mass_vsq_prime[ixnode][iynode][iznode] = 0.0;
sum_vsq_all[ixnode][iynode][iznode] = 0.0;
sum_vsq_prime_all[ixnode][iynode][iznode] = 0.0;
sum_mass_vsq_all[ixnode][iynode][iznode] = 0.0;
sum_mass_vsq_prime_all[ixnode][iynode][iznode] = 0.0;
}
}
}
for (int i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
double mass = atom->mass[type[i]];
double xscale = (x[i][0] - domain->boxlo[0])/domain->xprd;
double yscale = (x[i][1] - domain->boxlo[1])/domain->yprd;
double zscale = (x[i][2] - domain->boxlo[2])/domain->zprd;
int ixnode = static_cast<int>(xscale*nxnodes);
int iynode = static_cast<int>(yscale*nynodes);
int iznode = static_cast<int>(zscale*nznodes);
while (ixnode > nxnodes-1) ixnode -= nxnodes;
while (iynode > nynodes-1) iynode -= nynodes;
while (iznode > nznodes-1) iznode -= nznodes;
while (ixnode < 0) ixnode += nxnodes;
while (iynode < 0) iynode += nynodes;
while (iznode < 0) iznode += nznodes;
double vsq = v[i][0]*v[i][0] + v[i][1]*v[i][1] + v[i][2]*v[i][2];
nsum[ixnode][iynode][iznode] += 1;
sum_vsq[ixnode][iynode][iznode] += vsq;
sum_mass_vsq[ixnode][iynode][iznode] += mass*vsq;
if (vsq > v_0_sq) {
nsum_prime[ixnode][iynode][iznode] += 1;
sum_vsq_prime[ixnode][iynode][iznode] += vsq;
sum_mass_vsq_prime[ixnode][iynode][iznode] += mass*vsq;
}
}
}
double dx = domain->xprd/nxnodes;
double dy = domain->yprd/nynodes;
double dz = domain->zprd/nznodes;
double del_vol = dx*dy*dz;
MPI_Allreduce(&nsum[0][0][0],&nsum_all[0][0][0],total_nnodes,MPI_INT,MPI_SUM,world);
MPI_Allreduce(&nsum_prime[0][0][0],&nsum_prime_all[0][0][0],total_nnodes,MPI_INT,MPI_SUM,world);
MPI_Allreduce(&sum_vsq[0][0][0],&sum_vsq_all[0][0][0],total_nnodes,MPI_DOUBLE,MPI_SUM,world);
MPI_Allreduce(&sum_vsq_prime[0][0][0],&sum_vsq_prime_all[0][0][0],total_nnodes,MPI_DOUBLE,MPI_SUM,world);
MPI_Allreduce(&sum_mass_vsq[0][0][0],&sum_mass_vsq_all[0][0][0],total_nnodes,MPI_DOUBLE,MPI_SUM,world);
MPI_Allreduce(&sum_mass_vsq_prime[0][0][0],&sum_mass_vsq_prime_all[0][0][0],total_nnodes,MPI_DOUBLE,MPI_SUM,world);
double max_g_p = 0.0;
for (int ixnode = 0; ixnode < nxnodes; ixnode++) {
for (int iynode = 0; iynode < nynodes; iynode++) {
for (int iznode = 0; iznode < nznodes; iznode++) {
if (nsum_all[ixnode][iynode][iznode] > 0) {
T_a[ixnode][iynode][iznode] = sum_mass_vsq_all[ixnode][iynode][iznode]/
(3*force->boltz*nsum_all[ixnode][iynode][iznode]/force->mvv2e);
double g_p_tmp = gamma_p*sum_vsq_all[ixnode][iynode][iznode]/
T_a[ixnode][iynode][iznode]/del_vol;
max_g_p = MAX(max_g_p,g_p_tmp);
g_p[ixnode][iynode][iznode] = g_p_tmp;
} else {
T_a[ixnode][iynode][iznode] = 0;
g_p[ixnode][iynode][iznode] = 0;
}
if (nsum_prime_all[ixnode][iynode][iznode] > 0) {
T_a_prime[ixnode][iynode][iznode] = sum_mass_vsq_prime_all[ixnode][iynode][iznode]/
(3*force->boltz*nsum_prime_all[ixnode][iynode][iznode]/force->mvv2e);
g_s[ixnode][iynode][iznode] = gamma_s*sum_vsq_prime_all[ixnode][iynode][iznode]/
T_a_prime[ixnode][iynode][iznode]/del_vol;
} else {
T_a_prime[ixnode][iynode][iznode] = 0;
g_s[ixnode][iynode][iznode] = 0;
}
}
}
}
// figure out how many inner steps (thermal solves) are required this MD timestep in order to maintain a stable explicit solve
int num_inner_timesteps = 1;
double inner_dt = update->dt;
double stability_criterion = 1.0 - 2.0*inner_dt/(electronic_specific_heat*electronic_density)*
(electronic_thermal_conductivity*(1/dx/dx + 1/dy/dy + 1/dz/dz) + 0.5*max_g_p);
if (stability_criterion < 0.0) {
inner_dt = 0.5*(electronic_specific_heat*electronic_density)/(electronic_thermal_conductivity*(1/dx/dx + 1/dy/dy + 1/dz/dz) + 0.5*max_g_p);
num_inner_timesteps = static_cast<int>(update->dt/inner_dt) + 1;
inner_dt = update->dt/double(num_inner_timesteps);
if (num_inner_timesteps > 1e6) error->warning("In the TTM fix, trying to do more than a million inner timesteps!");
}
for (int ith_inner_timestep = 0; ith_inner_timestep < num_inner_timesteps; ith_inner_timestep++) {
for (int ixnode = 0; ixnode < nxnodes; ixnode++) {
for (int iynode = 0; iynode < nynodes; iynode++) {
for (int iznode = 0; iznode < nznodes; iznode++) {
T_electron_old[ixnode][iynode][iznode] = T_electron[ixnode][iynode][iznode];
}
}
}
// compute new electron T profile
for (int ixnode = 0; ixnode < nxnodes; ixnode++) {
for (int iynode = 0; iynode < nynodes; iynode++) {
for (int iznode = 0; iznode < nznodes; iznode++) {
int right_xnode = ixnode + 1;
int right_ynode = iynode + 1;
int right_znode = iznode + 1;
if (right_xnode == nxnodes) right_xnode = 0;
if (right_ynode == nynodes) right_ynode = 0;
if (right_znode == nznodes) right_znode = 0;
int left_xnode = ixnode - 1;
int left_ynode = iynode - 1;
int left_znode = iznode - 1;
if (left_xnode == -1) left_xnode = nxnodes - 1;
if (left_ynode == -1) left_ynode = nynodes - 1;
if (left_znode == -1) left_znode = nznodes - 1;
T_electron[ixnode][iynode][iznode] = T_electron_old[ixnode][iynode][iznode] +
inner_dt/(electronic_specific_heat*electronic_density)*(electronic_thermal_conductivity*
((T_electron_old[right_xnode][iynode][iznode] + T_electron_old[left_xnode][iynode][iznode] - 2*T_electron_old[ixnode][iynode][iznode])/dx/dx +
(T_electron_old[ixnode][right_ynode][iznode] + T_electron_old[ixnode][left_ynode][iznode] - 2*T_electron_old[ixnode][iynode][iznode])/dy/dy +
(T_electron_old[ixnode][iynode][right_znode] + T_electron_old[ixnode][iynode][left_znode] - 2*T_electron_old[ixnode][iynode][iznode])/dz/dz) +
g_p[ixnode][iynode][iznode]*(T_a[ixnode][iynode][iznode] - T_electron_old[ixnode][iynode][iznode]) +
g_s[ixnode][iynode][iznode]*T_a_prime[ixnode][iynode][iznode]);
}
}
}
}
if (!(update->ntimestep % nfileevery) && (me == 0)) {
fprintf(fp,"%d ",update->ntimestep);
// print nodal temperatures for current timestep
for (int ixnode = 0; ixnode < nxnodes; ixnode++) {
for (int iynode = 0; iynode < nynodes; iynode++) {
for (int iznode = 0; iznode < nznodes; iznode++) {
fprintf(fp,"%f ",T_a[ixnode][iynode][iznode]);
}
}
}
fprintf(fp,"\t");
for (int ixnode = 0; ixnode < nxnodes; ixnode++) {
for (int iynode = 0; iynode < nynodes; iynode++) {
for (int iznode = 0; iznode < nznodes; iznode++) {
fprintf(fp,"%f ",T_electron[ixnode][iynode][iznode]);
}
}
}
fprintf(fp,"\n");
}
}

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src/fix_ttm.h Normal file
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@ -0,0 +1,53 @@
/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#ifndef FIX_TTM_H
#define FIX_TTM_H
#include "fix.h"
namespace LAMMPS_NS {
class FixTTM : public Fix {
public:
FixTTM(class LAMMPS *, int, char **);
~FixTTM();
int setmask();
void init();
void read_initial_electron_temperatures();
void setup(int);
void post_force(int);
void post_force_respa(int, int, int);
void reset_dt();
void update_electron_temperatures();
private:
int me;
int nfileevery;
int nlevels_respa;
class RanMars *random;
FILE *fp, *fpr;
int nxnodes,nynodes,nznodes,total_nnodes;
int ***nsum, ***nsum_prime, ***nsum_all, ***nsum_prime_all, ***T_initial_set;
double *gfactor1,*gfactor2,*ratio;
double ***T_electron, ***T_a, ***T_a_prime, ***g_p, ***g_s;
double ***sum_vsq, ***sum_vsq_prime, ***sum_mass_vsq, ***sum_mass_vsq_prime;
double ***sum_vsq_all, ***sum_vsq_prime_all, ***sum_mass_vsq_all, ***sum_mass_vsq_prime_all;
double ***T_electron_old;
double electronic_specific_heat,electronic_density,electronic_thermal_conductivity;
double gamma_p,gamma_s,v_0,v_0_sq;
};
}
#endif

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@ -194,6 +194,7 @@ DumpStyle(xyz,DumpXYZ)
#include "fix_temp_rescale.h"
#include "fix_thermal_conductivity.h"
#include "fix_tmd.h"
#include "fix_ttm.h"
#include "fix_viscosity.h"
#include "fix_viscous.h"
#include "fix_wall_lj126.h"
@ -255,6 +256,7 @@ FixStyle(temp/berendsen,FixTempBerendsen)
FixStyle(temp/rescale,FixTempRescale)
FixStyle(thermal/conductivity,FixThermalConductivity)
FixStyle(tmd,FixTMD)
FixStyle(ttm,FixTTM)
FixStyle(viscosity,FixViscosity)
FixStyle(viscous,FixViscous)
FixStyle(wall/lj126,FixWallLJ126)