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Adding new ptemp keyword to fix nh

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This commit is contained in:
jtclemm
2020-05-11 14:34:00 -06:00
parent 14fb49c1cb
commit 9b99ad271f
3 changed files with 44 additions and 6 deletions
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25
src/fix_nh.cpp Normal file → Executable file
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@ -39,6 +39,7 @@ using namespace FixConst;
#define DELTAFLIP 0.1
#define TILTMAX 1.5
#define EPSILON 1.0e-6
enum{NOBIAS,BIAS};
enum{NONE,XYZ,XY,YZ,XZ};
@ -83,6 +84,7 @@ FixNH::FixNH(LAMMPS *lmp, int narg, char **arg) :
flipflag = 1;
dipole_flag = 0;
dlm_flag = 0;
p_temp_flag = 0;
tcomputeflag = 0;
pcomputeflag = 0;
@ -259,6 +261,12 @@ FixNH::FixNH(LAMMPS *lmp, int narg, char **arg) :
drag = force->numeric(FLERR,arg[iarg+1]);
if (drag < 0.0) error->all(FLERR,"Illegal fix nvt/npt/nph command");
iarg += 2;
} else if (strcmp(arg[iarg],"ptemp") == 0) {
if (iarg+2 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
p_temp = force->numeric(FLERR,arg[iarg+1]);
p_temp_flag = 1;
if (p_temp <= 0.0) error->all(FLERR,"Illegal fix nvt/npt/nph command");
iarg += 2;
} else if (strcmp(arg[iarg],"dilate") == 0) {
if (iarg+2 > narg) error->all(FLERR,"Illegal fix nvt/npt/nph command");
if (strcmp(arg[iarg+1],"all") == 0) allremap = 1;
@ -466,6 +474,10 @@ FixNH::FixNH(LAMMPS *lmp, int narg, char **arg) :
(p_flag[5] && p_period[5] <= 0.0))
error->all(FLERR,"Fix nvt/npt/nph damping parameters must be > 0.0");
// check that ptemp is not defined with a thermostat
if (tstat_flag && p_temp_flag)
error->all(FLERR,"Thermostat in fix nvt/npt/nph is incompatible with ptemp command");
// set pstat_flag and box change and restart_pbc variables
pre_exchange_flag = 0;
@ -760,16 +772,19 @@ void FixNH::setup(int /*vflag*/)
} else if (pstat_flag) {
// t0 = reference temperature for masses
// set equal to either ptemp or the current temperature
// cannot be done in init() b/c temperature cannot be called there
// is b/c Modify::init() inits computes after fixes due to dof dependence
// guesstimate a unit-dependent t0 if actual T = 0.0
// error if T less than 1e-6
// if it was read in from a restart file, leave it be
if (t0 == 0.0) {
t0 = temperature->compute_scalar();
if (t0 == 0.0) {
if (strcmp(update->unit_style,"lj") == 0) t0 = 1.0;
else t0 = 300.0;
if(p_temp_flag) {
t0 = p_temp;
} else {
t0 = temperature->compute_scalar();
if(t0 < EPSILON)
error->all(FLERR, "Current temperature too close to zero, consider using ptemp setting");
}
}
t_target = t0;