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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15109 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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sjplimp
2016-06-06 23:21:39 +00:00
parent 1a52795e1d
commit 0f3e4182e8
67 changed files with 236 additions and 151 deletions
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36
src/fix_spring.cpp
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@ -47,6 +47,7 @@ FixSpring::FixSpring(LAMMPS *lmp, int narg, char **arg) :
global_freq = 1;
extscalar = 1;
extvector = 1;
dynamic_group_allow = 1;
group2 = NULL;
@ -166,6 +167,10 @@ void FixSpring::post_force(int vflag)
void FixSpring::spring_tether()
{
double xcm[3];
if (group->dynamic[igroup])
masstotal = group->mass(igroup);
group->xcm(igroup,masstotal,xcm);
// fx,fy,fz = components of k * (r-r0) / masstotal
@ -192,9 +197,11 @@ void FixSpring::spring_tether()
if (dr < 0.0) ftotal[3] = -ftotal[3];
espring = 0.5*k_spring * dr*dr;
fx /= masstotal;
fy /= masstotal;
fz /= masstotal;
if (masstotal > 0.0) {
fx /= masstotal;
fy /= masstotal;
fz /= masstotal;
}
// apply restoring force to atoms in group
@ -231,6 +238,13 @@ void FixSpring::spring_tether()
void FixSpring::spring_couple()
{
double xcm[3],xcm2[3];
if (group->dynamic[igroup])
masstotal = group->mass(igroup);
if (group->dynamic[igroup2])
masstotal2 = group->mass(igroup2);
group->xcm(igroup,masstotal,xcm);
group->xcm(igroup2,masstotal2,xcm2);
@ -259,12 +273,16 @@ void FixSpring::spring_couple()
if (dr < 0.0) ftotal[3] = -ftotal[3];
espring = 0.5*k_spring * dr*dr;
fx2 = fx/masstotal2;
fy2 = fy/masstotal2;
fz2 = fz/masstotal2;
fx /= masstotal;
fy /= masstotal;
fz /= masstotal;
if (masstotal2 > 0.0) {
fx2 = fx/masstotal2;
fy2 = fy/masstotal2;
fz2 = fz/masstotal2;
}
if (masstotal > 0.0) {
fx /= masstotal;
fy /= masstotal;
fz /= masstotal;
}
// apply restoring force to atoms in group
// f = -k*(r-r0)*mass/masstotal