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add ability to set multiplicity for dihedrals with fix restrain

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this introduces an optional keyword, so backward compatibility is preserved.
this closes #884
This commit is contained in:
Axel Kohlmeyer
2018-05-06 21:41:09 -04:00
parent d51745fd27
commit d9d33ac766
3 changed files with 24 additions and 10 deletions
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19
src/fix_restrain.cpp
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@ -45,7 +45,7 @@ enum{BOND,ANGLE,DIHEDRAL};
FixRestrain::FixRestrain(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg),
rstyle(NULL), ids(NULL), kstart(NULL), kstop(NULL), target(NULL),
rstyle(NULL), mult(NULL), ids(NULL), kstart(NULL), kstop(NULL), target(NULL),
cos_target(NULL), sin_target(NULL)
{
if (narg < 4) error->all(FLERR,"Illegal fix restrain command");
@ -65,6 +65,7 @@ FixRestrain::FixRestrain(LAMMPS *lmp, int narg, char **arg) :
if (nrestrain == maxrestrain) {
maxrestrain += DELTA;
memory->grow(rstyle,maxrestrain,"restrain:rstyle");
memory->grow(mult,maxrestrain,"restrain:mult");
memory->grow(ids,maxrestrain,4,"restrain:ids");
memory->grow(kstart,maxrestrain,"restrain:kstart");
memory->grow(kstop,maxrestrain,"restrain:kstop");
@ -96,6 +97,7 @@ FixRestrain::FixRestrain(LAMMPS *lmp, int narg, char **arg) :
} else if (strcmp(arg[iarg],"dihedral") == 0) {
if (iarg+8 > narg) error->all(FLERR,"Illegal fix restrain command");
rstyle[nrestrain] = DIHEDRAL;
mult[nrestrain] = 1;
ids[nrestrain][0] = force->inumeric(FLERR,arg[iarg+1]);
ids[nrestrain][1] = force->inumeric(FLERR,arg[iarg+2]);
ids[nrestrain][2] = force->inumeric(FLERR,arg[iarg+3]);
@ -107,6 +109,13 @@ FixRestrain::FixRestrain(LAMMPS *lmp, int narg, char **arg) :
cos_target[nrestrain] = cos(target[nrestrain]);
sin_target[nrestrain] = sin(target[nrestrain]);
iarg += 8;
if ((iarg < narg) && (strcmp("mult",arg[iarg]) == 0)) {
if (iarg+1 > narg) error->all(FLERR,"Illegal fix restrain command");
mult[nrestrain] = force->inumeric(FLERR,arg[iarg+1]);
if (mult[nrestrain] < 0)
error->all(FLERR,"Illegal fix restrain command");
iarg += 2;
}
} else error->all(FLERR,"Illegal fix restrain command");
nrestrain++;
@ -123,6 +132,7 @@ FixRestrain::FixRestrain(LAMMPS *lmp, int narg, char **arg) :
FixRestrain::~FixRestrain()
{
memory->destroy(rstyle);
memory->destroy(mult);
memory->destroy(ids);
memory->destroy(kstart);
memory->destroy(kstop);
@ -410,7 +420,7 @@ void FixRestrain::restrain_angle(int m)
void FixRestrain::restrain_dihedral(int m)
{
int i1,i2,i3,i4,i,mult;
int i1,i2,i3,i4,i;
double vb1x,vb1y,vb1z,vb2x,vb2y,vb2z,vb3x,vb3y,vb3z,vb2xm,vb2ym,vb2zm;
double f1[3],f2[3],f3[3],f4[3];
double ax,ay,az,bx,by,bz,rasq,rbsq,rgsq,rg,rginv,ra2inv,rb2inv,rabinv;
@ -534,11 +544,10 @@ void FixRestrain::restrain_dihedral(int m)
if (c > 1.0) c = 1.0;
if (c < -1.0) c = -1.0;
mult = 1; // multiplicity
p = 1.0;
df1 = 0.0;
for (i = 0; i < mult; i++) {
for (i = 0; i < mult[m]; i++) {
ddf1 = p*c - df1*s;
df1 = p*s + df1*c;
p = ddf1;
@ -546,7 +555,7 @@ void FixRestrain::restrain_dihedral(int m)
p = p*cos_target[m] + df1*sin_target[m];
df1 = df1*cos_target[m] - ddf1*sin_target[m];
df1 *= -mult;
df1 *= -mult[m];
p += 1.0;
energy += k * p;