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lammps/src/USER-OMP/improper_harmonic_omp.cpp
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improper_harmonic_omp.cpp
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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.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing author: Axel Kohlmeyer (Temple U)
------------------------------------------------------------------------- */
#include "math.h"
#include "improper_harmonic_omp.h"
#include "atom.h"
#include "comm.h"
#include "neighbor.h"
#include "domain.h"
#include "force.h"
#include "update.h"
#include "error.h"
#include "suffix.h"
using namespace LAMMPS_NS;
#define TOLERANCE 0.05
#define SMALL 0.001
/* ---------------------------------------------------------------------- */
ImproperHarmonicOMP::ImproperHarmonicOMP(class LAMMPS *lmp)
: ImproperHarmonic(lmp), ThrOMP(lmp,THR_IMPROPER)
{
suffix_flag |= Suffix::OMP;
}
/* ---------------------------------------------------------------------- */
void ImproperHarmonicOMP::compute(int eflag, int vflag)
{
if (eflag || vflag) {
ev_setup(eflag,vflag);
} else evflag = 0;
const int nall = atom->nlocal + atom->nghost;
const int nthreads = comm->nthreads;
const int inum = neighbor->nimproperlist;
#if defined(_OPENMP)
#pragma omp parallel default(none) shared(eflag,vflag)
#endif
{
int ifrom, ito, tid;
loop_setup_thr(ifrom, ito, tid, inum, nthreads);
ThrData *thr = fix->get_thr(tid);
ev_setup_thr(eflag, vflag, nall, eatom, vatom, thr);
if (evflag) {
if (eflag) {
if (force->newton_bond) eval<1,1,1>(ifrom, ito, thr);
else eval<1,1,0>(ifrom, ito, thr);
} else {
if (force->newton_bond) eval<1,0,1>(ifrom, ito, thr);
else eval<1,0,0>(ifrom, ito, thr);
}
} else {
if (force->newton_bond) eval<0,0,1>(ifrom, ito, thr);
else eval<0,0,0>(ifrom, ito, thr);
}
reduce_thr(this, eflag, vflag, thr);
} // end of omp parallel region
}
template <int EVFLAG, int EFLAG, int NEWTON_BOND>
void ImproperHarmonicOMP::eval(int nfrom, int nto, ThrData * const thr)
{
int i1,i2,i3,i4,n,type;
double vb1x,vb1y,vb1z,vb2x,vb2y,vb2z,vb3x,vb3y,vb3z;
double eimproper,f1[3],f2[3],f3[3],f4[3];
double ss1,ss2,ss3,r1,r2,r3,c0,c1,c2,s1,s2;
double s12,c,s,domega,a,a11,a22,a33,a12,a13,a23;
double sx2,sy2,sz2;
eimproper = 0.0;
const double * const * const x = atom->x;
double * const * const f = thr->get_f();
const int * const * const improperlist = neighbor->improperlist;
const int nlocal = atom->nlocal;
for (n = nfrom; n < nto; n++) {
i1 = improperlist[n][0];
i2 = improperlist[n][1];
i3 = improperlist[n][2];
i4 = improperlist[n][3];
type = improperlist[n][4];
// geometry of 4-body
vb1x = x[i1][0] - x[i2][0];
vb1y = x[i1][1] - x[i2][1];
vb1z = x[i1][2] - x[i2][2];
domain->minimum_image(vb1x,vb1y,vb1z);
vb2x = x[i3][0] - x[i2][0];
vb2y = x[i3][1] - x[i2][1];
vb2z = x[i3][2] - x[i2][2];
domain->minimum_image(vb2x,vb2y,vb2z);
vb3x = x[i4][0] - x[i3][0];
vb3y = x[i4][1] - x[i3][1];
vb3z = x[i4][2] - x[i3][2];
domain->minimum_image(vb3x,vb3y,vb3z);
ss1 = 1.0 / (vb1x*vb1x + vb1y*vb1y + vb1z*vb1z);
ss2 = 1.0 / (vb2x*vb2x + vb2y*vb2y + vb2z*vb2z);
ss3 = 1.0 / (vb3x*vb3x + vb3y*vb3y + vb3z*vb3z);
r1 = sqrt(ss1);
r2 = sqrt(ss2);
r3 = sqrt(ss3);
// sin and cos of angle
c0 = (vb1x * vb3x + vb1y * vb3y + vb1z * vb3z) * r1 * r3;
c1 = (vb1x * vb2x + vb1y * vb2y + vb1z * vb2z) * r1 * r2;
c2 = -(vb3x * vb2x + vb3y * vb2y + vb3z * vb2z) * r3 * r2;
s1 = 1.0 - c1*c1;
if (s1 < SMALL) s1 = SMALL;
s1 = 1.0 / s1;
s2 = 1.0 - c2*c2;
if (s2 < SMALL) s2 = SMALL;
s2 = 1.0 / s2;
s12 = sqrt(s1*s2);
c = (c1*c2 + c0) * s12;
// error check
if (c > 1.0 + TOLERANCE || c < (-1.0 - TOLERANCE)) {
int me = comm->me;
if (screen) {
char str[128];
sprintf(str,"Improper problem: %d/%d " BIGINT_FORMAT " %d %d %d %d",
me,thr->get_tid(),update->ntimestep,
atom->tag[i1],atom->tag[i2],atom->tag[i3],atom->tag[i4]);
error->warning(FLERR,str,0);
fprintf(screen," 1st atom: %d %g %g %g\n",
me,x[i1][0],x[i1][1],x[i1][2]);
fprintf(screen," 2nd atom: %d %g %g %g\n",
me,x[i2][0],x[i2][1],x[i2][2]);
fprintf(screen," 3rd atom: %d %g %g %g\n",
me,x[i3][0],x[i3][1],x[i3][2]);
fprintf(screen," 4th atom: %d %g %g %g\n",
me,x[i4][0],x[i4][1],x[i4][2]);
}
}
if (c > 1.0) c = 1.0;
if (c < -1.0) c = -1.0;
s = sqrt(1.0 - c*c);
if (s < SMALL) s = SMALL;
// force & energy
domega = acos(c) - chi[type];
a = k[type] * domega;
if (EFLAG) eimproper = a*domega;
a = -a * 2.0/s;
c = c * a;
s12 = s12 * a;
a11 = c*ss1*s1;
a22 = -ss2 * (2.0*c0*s12 - c*(s1+s2));
a33 = c*ss3*s2;
a12 = -r1*r2*(c1*c*s1 + c2*s12);
a13 = -r1*r3*s12;
a23 = r2*r3*(c2*c*s2 + c1*s12);
sx2 = a22*vb2x + a23*vb3x + a12*vb1x;
sy2 = a22*vb2y + a23*vb3y + a12*vb1y;
sz2 = a22*vb2z + a23*vb3z + a12*vb1z;
f1[0] = a12*vb2x + a13*vb3x + a11*vb1x;
f1[1] = a12*vb2y + a13*vb3y + a11*vb1y;
f1[2] = a12*vb2z + a13*vb3z + a11*vb1z;
f2[0] = -sx2 - f1[0];
f2[1] = -sy2 - f1[1];
f2[2] = -sz2 - f1[2];
f4[0] = a23*vb2x + a33*vb3x + a13*vb1x;
f4[1] = a23*vb2y + a33*vb3y + a13*vb1y;
f4[2] = a23*vb2z + a33*vb3z + a13*vb1z;
f3[0] = sx2 - f4[0];
f3[1] = sy2 - f4[1];
f3[2] = sz2 - f4[2];
// apply force to each of 4 atoms
if (NEWTON_BOND || i1 < nlocal) {
f[i1][0] += f1[0];
f[i1][1] += f1[1];
f[i1][2] += f1[2];
}
if (NEWTON_BOND || i2 < nlocal) {
f[i2][0] += f2[0];
f[i2][1] += f2[1];
f[i2][2] += f2[2];
}
if (NEWTON_BOND || i3 < nlocal) {
f[i3][0] += f3[0];
f[i3][1] += f3[1];
f[i3][2] += f3[2];
}
if (NEWTON_BOND || i4 < nlocal) {
f[i4][0] += f4[0];
f[i4][1] += f4[1];
f[i4][2] += f4[2];
}
if (EVFLAG)
ev_tally_thr(this,i1,i2,i3,i4,nlocal,NEWTON_BOND,eimproper,f1,f3,f4,
vb1x,vb1y,vb1z,vb2x,vb2y,vb2z,vb3x,vb3y,vb3z,thr);
}
}
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