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dihedral_class2_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 "lmptype.h"
#include "mpi.h"
#include "math.h"
#include "dihedral_class2_omp.h"
#include "atom.h"
#include "comm.h"
#include "neighbor.h"
#include "domain.h"
#include "force.h"
#include "update.h"
#include "error.h"
using namespace LAMMPS_NS;
#define TOLERANCE 0.05
#define SMALL 0.0000001
/* ---------------------------------------------------------------------- */
void DihedralClass2OMP::compute(int eflag, int vflag)
{
if (eflag || vflag) {
ev_setup(eflag,vflag);
ev_setup_thr(this);
} else evflag = 0;
const int nall = atom->nlocal + atom->nghost;
const int nthreads = comm->nthreads;
const int inum = neighbor->ndihedrallist;
#if defined(_OPENMP)
#pragma omp parallel default(shared)
#endif
{
int ifrom, ito, tid;
double **f;
f = loop_setup_thr(atom->f, ifrom, ito, tid, inum, nall, nthreads);
if (evflag) {
if (eflag) {
if (force->newton_bond) eval<1,1,1>(f, ifrom, ito, tid);
else eval<1,1,0>(f, ifrom, ito, tid);
} else {
if (force->newton_bond) eval<1,0,1>(f, ifrom, ito, tid);
else eval<1,0,0>(f, ifrom, ito, tid);
}
} else {
if (force->newton_bond) eval<0,0,1>(f, ifrom, ito, tid);
else eval<0,0,0>(f, ifrom, ito, tid);
}
// reduce per thread forces into global force array.
data_reduce_thr(&(atom->f[0][0]), nall, nthreads, 3, tid);
} // end of omp parallel region
// reduce per thread energy and virial, if requested.
if (evflag) ev_reduce_thr(this);
}
template <int EVFLAG, int EFLAG, int NEWTON_BOND>
void DihedralClass2OMP::eval(double **f, int nfrom, int nto, int tid)
{
int i1,i2,i3,i4,i,j,k,n,type;
double vb1x,vb1y,vb1z,vb2x,vb2y,vb2z,vb3x,vb3y,vb3z,vb2xm,vb2ym,vb2zm;
double edihedral;
double r1mag2,r1,r2mag2,r2,r3mag2,r3;
double sb1,rb1,sb2,rb2,sb3,rb3,c0,r12c1;
double r12c2,costh12,costh13,costh23,sc1,sc2,s1,s2,c;
double cosphi,phi,sinphi,a11,a22,a33,a12,a13,a23,sx1,sx2;
double sx12,sy1,sy2,sy12,sz1,sz2,sz12,dphi1,dphi2,dphi3;
double de_dihedral,t1,t2,t3,t4,cos2phi,cos3phi,bt1,bt2;
double bt3,sumbte,db,sumbtf,at1,at2,at3,da,da1,da2,r1_0;
double r3_0,dr1,dr2,tk1,tk2,s12,sin2;
double dcosphidr[4][3],dphidr[4][3],dbonddr[3][4][3],dthetadr[2][4][3];
double fabcd[4][3];
edihedral = 0.0;
double **x = atom->x;
int **dihedrallist = neighbor->dihedrallist;
int nlocal = atom->nlocal;
for (n = nfrom; n < nto; n++) {
i1 = dihedrallist[n][0];
i2 = dihedrallist[n][1];
i3 = dihedrallist[n][2];
i4 = dihedrallist[n][3];
type = dihedrallist[n][4];
// 1st bond
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);
// 2nd bond
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);
vb2xm = -vb2x;
vb2ym = -vb2y;
vb2zm = -vb2z;
domain->minimum_image(vb2xm,vb2ym,vb2zm);
// 3rd bond
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);
// distances
r1mag2 = vb1x*vb1x + vb1y*vb1y + vb1z*vb1z;
r1 = sqrt(r1mag2);
r2mag2 = vb2x*vb2x + vb2y*vb2y + vb2z*vb2z;
r2 = sqrt(r2mag2);
r3mag2 = vb3x*vb3x + vb3y*vb3y + vb3z*vb3z;
r3 = sqrt(r3mag2);
sb1 = 1.0/r1mag2;
rb1 = 1.0/r1;
sb2 = 1.0/r2mag2;
rb2 = 1.0/r2;
sb3 = 1.0/r3mag2;
rb3 = 1.0/r3;
c0 = (vb1x*vb3x + vb1y*vb3y + vb1z*vb3z) * rb1*rb3;
// angles
r12c1 = rb1*rb2;
r12c2 = rb2*rb3;
costh12 = (vb1x*vb2x + vb1y*vb2y + vb1z*vb2z) * r12c1;
costh13 = c0;
costh23 = (vb2xm*vb3x + vb2ym*vb3y + vb2zm*vb3z) * r12c2;
// cos and sin of 2 angles and final c
sin2 = MAX(1.0 - costh12*costh12,0.0);
sc1 = sqrt(sin2);
if (sc1 < SMALL) sc1 = SMALL;
sc1 = 1.0/sc1;
sin2 = MAX(1.0 - costh23*costh23,0.0);
sc2 = sqrt(sin2);
if (sc2 < SMALL) sc2 = SMALL;
sc2 = 1.0/sc2;
s1 = sc1 * sc1;
s2 = sc2 * sc2;
s12 = sc1 * sc2;
c = (c0 + costh12*costh23) * s12;
// error check
if (c > 1.0 + TOLERANCE || c < (-1.0 - TOLERANCE)) {
int me;
MPI_Comm_rank(world,&me);
if (screen) {
char str[128];
sprintf(str,"Dihedral problem: %d " BIGINT_FORMAT " %d %d %d %d",
me,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;
cosphi = c;
phi = acos(c);
sinphi = sqrt(1.0 - c*c);
sinphi = MAX(sinphi,SMALL);
a11 = -c*sb1*s1;
a22 = sb2 * (2.0*costh13*s12 - c*(s1+s2));
a33 = -c*sb3*s2;
a12 = r12c1 * (costh12*c*s1 + costh23*s12);
a13 = rb1*rb3*s12;
a23 = r12c2 * (-costh23*c*s2 - costh12*s12);
sx1 = a11*vb1x + a12*vb2x + a13*vb3x;
sx2 = a12*vb1x + a22*vb2x + a23*vb3x;
sx12 = a13*vb1x + a23*vb2x + a33*vb3x;
sy1 = a11*vb1y + a12*vb2y + a13*vb3y;
sy2 = a12*vb1y + a22*vb2y + a23*vb3y;
sy12 = a13*vb1y + a23*vb2y + a33*vb3y;
sz1 = a11*vb1z + a12*vb2z + a13*vb3z;
sz2 = a12*vb1z + a22*vb2z + a23*vb3z;
sz12 = a13*vb1z + a23*vb2z + a33*vb3z;
// set up d(cos(phi))/d(r) and dphi/dr arrays
dcosphidr[0][0] = -sx1;
dcosphidr[0][1] = -sy1;
dcosphidr[0][2] = -sz1;
dcosphidr[1][0] = sx2 + sx1;
dcosphidr[1][1] = sy2 + sy1;
dcosphidr[1][2] = sz2 + sz1;
dcosphidr[2][0] = sx12 - sx2;
dcosphidr[2][1] = sy12 - sy2;
dcosphidr[2][2] = sz12 - sz2;
dcosphidr[3][0] = -sx12;
dcosphidr[3][1] = -sy12;
dcosphidr[3][2] = -sz12;
for (i = 0; i < 4; i++)
for (j = 0; j < 3; j++)
dphidr[i][j] = -dcosphidr[i][j] / sinphi;
// energy
dphi1 = phi - phi1[type];
dphi2 = 2.0*phi - phi2[type];
dphi3 = 3.0*phi - phi3[type];
if (EFLAG) edihedral = k1[type]*(1.0 - cos(dphi1)) +
k2[type]*(1.0 - cos(dphi2)) +
k3[type]*(1.0 - cos(dphi3));
de_dihedral = k1[type]*sin(dphi1) + 2.0*k2[type]*sin(dphi2) +
3.0*k3[type]*sin(dphi3);
// torsion forces on all 4 atoms
for (i = 0; i < 4; i++)
for (j = 0; j < 3; j++)
fabcd[i][j] = de_dihedral*dphidr[i][j];
// set up d(bond)/d(r) array
// dbonddr(i,j,k) = bond i, atom j, coordinate k
for (i = 0; i < 3; i++)
for (j = 0; j < 4; j++)
for (k = 0; k < 3; k++)
dbonddr[i][j][k] = 0.0;
// bond1
dbonddr[0][0][0] = vb1x / r1;
dbonddr[0][0][1] = vb1y / r1;
dbonddr[0][0][2] = vb1z / r1;
dbonddr[0][1][0] = -vb1x / r1;
dbonddr[0][1][1] = -vb1y / r1;
dbonddr[0][1][2] = -vb1z / r1;
// bond2
dbonddr[1][1][0] = vb2x / r2;
dbonddr[1][1][1] = vb2y / r2;
dbonddr[1][1][2] = vb2z / r2;
dbonddr[1][2][0] = -vb2x / r2;
dbonddr[1][2][1] = -vb2y / r2;
dbonddr[1][2][2] = -vb2z / r2;
// bond3
dbonddr[2][2][0] = vb3x / r3;
dbonddr[2][2][1] = vb3y / r3;
dbonddr[2][2][2] = vb3z / r3;
dbonddr[2][3][0] = -vb3x / r3;
dbonddr[2][3][1] = -vb3y / r3;
dbonddr[2][3][2] = -vb3z / r3;
// set up d(theta)/d(r) array
// dthetadr(i,j,k) = angle i, atom j, coordinate k
for (i = 0; i < 2; i++)
for (j = 0; j < 4; j++)
for (k = 0; k < 3; k++)
dthetadr[i][j][k] = 0.0;
t1 = costh12 / r1mag2;
t2 = costh23 / r2mag2;
t3 = costh12 / r2mag2;
t4 = costh23 / r3mag2;
// angle12
dthetadr[0][0][0] = sc1 * ((t1 * vb1x) - (vb2x * r12c1));
dthetadr[0][0][1] = sc1 * ((t1 * vb1y) - (vb2y * r12c1));
dthetadr[0][0][2] = sc1 * ((t1 * vb1z) - (vb2z * r12c1));
dthetadr[0][1][0] = sc1 * ((-t1 * vb1x) + (vb2x * r12c1) +
(-t3 * vb2x) + (vb1x * r12c1));
dthetadr[0][1][1] = sc1 * ((-t1 * vb1y) + (vb2y * r12c1) +
(-t3 * vb2y) + (vb1y * r12c1));
dthetadr[0][1][2] = sc1 * ((-t1 * vb1z) + (vb2z * r12c1) +
(-t3 * vb2z) + (vb1z * r12c1));
dthetadr[0][2][0] = sc1 * ((t3 * vb2x) - (vb1x * r12c1));
dthetadr[0][2][1] = sc1 * ((t3 * vb2y) - (vb1y * r12c1));
dthetadr[0][2][2] = sc1 * ((t3 * vb2z) - (vb1z * r12c1));
// angle23
dthetadr[1][1][0] = sc2 * ((t2 * vb2x) + (vb3x * r12c2));
dthetadr[1][1][1] = sc2 * ((t2 * vb2y) + (vb3y * r12c2));
dthetadr[1][1][2] = sc2 * ((t2 * vb2z) + (vb3z * r12c2));
dthetadr[1][2][0] = sc2 * ((-t2 * vb2x) - (vb3x * r12c2) +
(t4 * vb3x) + (vb2x * r12c2));
dthetadr[1][2][1] = sc2 * ((-t2 * vb2y) - (vb3y * r12c2) +
(t4 * vb3y) + (vb2y * r12c2));
dthetadr[1][2][2] = sc2 * ((-t2 * vb2z) - (vb3z * r12c2) +
(t4 * vb3z) + (vb2z * r12c2));
dthetadr[1][3][0] = -sc2 * ((t4 * vb3x) + (vb2x * r12c2));
dthetadr[1][3][1] = -sc2 * ((t4 * vb3y) + (vb2y * r12c2));
dthetadr[1][3][2] = -sc2 * ((t4 * vb3z) + (vb2z * r12c2));
// mid-bond/torsion coupling
// energy on bond2 (middle bond)
cos2phi = cos(2.0*phi);
cos3phi = cos(3.0*phi);
bt1 = mbt_f1[type] * cosphi;
bt2 = mbt_f2[type] * cos2phi;
bt3 = mbt_f3[type] * cos3phi;
sumbte = bt1 + bt2 + bt3;
db = r2 - mbt_r0[type];
if (EFLAG) edihedral += db * sumbte;
// force on bond2
bt1 = -mbt_f1[type] * sinphi;
bt2 = -2.0 * mbt_f2[type] * sin(2.0*phi);
bt3 = -3.0 * mbt_f3[type] * sin(3.0*phi);
sumbtf = bt1 + bt2 + bt3;
for (i = 0; i < 4; i++)
for (j = 0; j < 3; j++)
fabcd[i][j] += db*sumbtf*dphidr[i][j] + sumbte*dbonddr[1][i][j];
// end-bond/torsion coupling
// energy on bond1 (first bond)
bt1 = ebt_f1_1[type] * cosphi;
bt2 = ebt_f2_1[type] * cos2phi;
bt3 = ebt_f3_1[type] * cos3phi;
sumbte = bt1 + bt2 + bt3;
db = r1 - ebt_r0_1[type];
if (EFLAG) edihedral += db * (bt1+bt2+bt3);
// force on bond1
bt1 = ebt_f1_1[type] * sinphi;
bt2 = 2.0 * ebt_f2_1[type] * sin(2.0*phi);
bt3 = 3.0 * ebt_f3_1[type] * sin(3.0*phi);
sumbtf = bt1 + bt2 + bt3;
for (i = 0; i < 4; i++)
for (j = 0; j < 3; j++)
fabcd[i][j] -= db*sumbtf*dphidr[i][j] + sumbte*dbonddr[0][i][j];
// end-bond/torsion coupling
// energy on bond3 (last bond)
bt1 = ebt_f1_2[type] * cosphi;
bt2 = ebt_f2_2[type] * cos2phi;
bt3 = ebt_f3_2[type] * cos3phi;
sumbte = bt1 + bt2 + bt3;
db = r3 - ebt_r0_2[type];
if (EFLAG) edihedral += db * (bt1+bt2+bt3);
// force on bond3
bt1 = -ebt_f1_2[type] * sinphi;
bt2 = -2.0 * ebt_f2_2[type] * sin(2.0*phi);
bt3 = -3.0 * ebt_f3_2[type] * sin(3.0*phi);
sumbtf = bt1 + bt2 + bt3;
for (i = 0; i < 4; i++)
for (j = 0; j < 3; j++)
fabcd[i][j] += db*sumbtf*dphidr[i][j] + sumbte*dbonddr[2][i][j];
// angle/torsion coupling
// energy on angle1
at1 = at_f1_1[type] * cosphi;
at2 = at_f2_1[type] * cos2phi;
at3 = at_f3_1[type] * cos3phi;
sumbte = at1 + at2 + at3;
da = acos(costh12) - at_theta0_1[type];
if (EFLAG) edihedral += da * (at1+at2+at3);
// force on angle1
bt1 = at_f1_1[type] * sinphi;
bt2 = 2.0 * at_f2_1[type] * sin(2.0*phi);
bt3 = 3.0 * at_f3_1[type] * sin(3.0*phi);
sumbtf = bt1 + bt2 + bt3;
for (i = 0; i < 4; i++)
for (j = 0; j < 3; j++)
fabcd[i][j] -= da*sumbtf*dphidr[i][j] + sumbte*dthetadr[0][i][j];
// energy on angle2
at1 = at_f1_2[type] * cosphi;
at2 = at_f2_2[type] * cos2phi;
at3 = at_f3_2[type] * cos3phi;
sumbte = at1 + at2 + at3;
da = acos(costh23) - at_theta0_2[type];
if (EFLAG) edihedral += da * (at1+at2+at3);
// force on angle2
bt1 = -at_f1_2[type] * sinphi;
bt2 = -2.0 * at_f2_2[type] * sin(2.0*phi);
bt3 = -3.0 * at_f3_2[type] * sin(3.0*phi);
sumbtf = bt1 + bt2 + bt3;
for (i = 0; i < 4; i++)
for (j = 0; j < 3; j++)
fabcd[i][j] += da*sumbtf*dphidr[i][j] + sumbte*dthetadr[1][i][j];
// angle/angle/torsion coupling
da1 = acos(costh12) - aat_theta0_1[type];
da2 = acos(costh23) - aat_theta0_2[type];
if (EFLAG) edihedral += aat_k[type]*da1*da2*cosphi;
for (i = 0; i < 4; i++)
for (j = 0; j < 3; j++)
fabcd[i][j] -= aat_k[type] *
(cosphi * (da2*dthetadr[0][i][j] - da1*dthetadr[1][i][j]) +
sinphi * da1*da2*dphidr[i][j]);
// bond1/bond3 coupling
if (fabs(bb13t_k[type]) > SMALL) {
r1_0 = bb13t_r10[type];
r3_0 = bb13t_r30[type];
dr1 = r1 - r1_0;
dr2 = r3 - r3_0;
tk1 = -bb13t_k[type] * dr1 / r3;
tk2 = -bb13t_k[type] * dr2 / r1;
if (EFLAG) edihedral += bb13t_k[type]*dr1*dr2;
fabcd[0][0] += tk2 * vb1x;
fabcd[0][1] += tk2 * vb1y;
fabcd[0][2] += tk2 * vb1z;
fabcd[1][0] -= tk2 * vb1x;
fabcd[1][1] -= tk2 * vb1y;
fabcd[1][2] -= tk2 * vb1z;
fabcd[2][0] -= tk1 * vb3x;
fabcd[2][1] -= tk1 * vb3y;
fabcd[2][2] -= tk1 * vb3z;
fabcd[3][0] += tk1 * vb3x;
fabcd[3][1] += tk1 * vb3y;
fabcd[3][2] += tk1 * vb3z;
}
// apply force to each of 4 atoms
if (NEWTON_BOND || i1 < nlocal) {
f[i1][0] += fabcd[0][0];
f[i1][1] += fabcd[0][1];
f[i1][2] += fabcd[0][2];
}
if (NEWTON_BOND || i2 < nlocal) {
f[i2][0] += fabcd[1][0];
f[i2][1] += fabcd[1][1];
f[i2][2] += fabcd[1][2];
}
if (NEWTON_BOND || i3 < nlocal) {
f[i3][0] += fabcd[2][0];
f[i3][1] += fabcd[2][1];
f[i3][2] += fabcd[2][2];
}
if (NEWTON_BOND || i4 < nlocal) {
f[i4][0] += fabcd[3][0];
f[i4][1] += fabcd[3][1];
f[i4][2] += fabcd[3][2];
}
if (EVFLAG)
ev_tally_thr(this,i1,i2,i3,i4,nlocal,NEWTON_BOND,edihedral,
fabcd[0],fabcd[2],fabcd[3],
vb1x,vb1y,vb1z,vb2x,vb2y,vb2z,vb3x,vb3y,vb3z,tid);
}
}

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