1 // clang-format off
2 /* ----------------------------------------------------------------------
3    LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
4    https://www.lammps.org/, Sandia National Laboratories
5    Steve Plimpton, sjplimp@sandia.gov
6 
7    Copyright (2003) Sandia Corporation.  Under the terms of Contract
8    DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
9    certain rights in this software.  This software is distributed under
10    the GNU General Public License.
11 
12    See the README file in the top-level LAMMPS directory.
13 ------------------------------------------------------------------------- */
14 
15 /* ----------------------------------------------------------------------
16    Contributing author: Axel Kohlmeyer (Temple U)
17 ------------------------------------------------------------------------- */
18 
19 #include "improper_cossq_omp.h"
20 
21 #include "atom.h"
22 #include "comm.h"
23 #include "force.h"
24 #include "neighbor.h"
25 
26 #include <cmath>
27 
28 #include "omp_compat.h"
29 #include "suffix.h"
30 using namespace LAMMPS_NS;
31 
32 #define TOLERANCE 0.05
33 #define SMALL     0.001
34 
35 /* ---------------------------------------------------------------------- */
36 
ImproperCossqOMP(class LAMMPS * lmp)37 ImproperCossqOMP::ImproperCossqOMP(class LAMMPS *lmp)
38   : ImproperCossq(lmp), ThrOMP(lmp,THR_IMPROPER)
39 {
40   suffix_flag |= Suffix::OMP;
41 }
42 
43 /* ---------------------------------------------------------------------- */
44 
compute(int eflag,int vflag)45 void ImproperCossqOMP::compute(int eflag, int vflag)
46 {
47   ev_init(eflag,vflag);
48 
49   const int nall = atom->nlocal + atom->nghost;
50   const int nthreads = comm->nthreads;
51   const int inum = neighbor->nimproperlist;
52 
53 #if defined(_OPENMP)
54 #pragma omp parallel LMP_DEFAULT_NONE LMP_SHARED(eflag,vflag)
55 #endif
56   {
57     int ifrom, ito, tid;
58 
59     loop_setup_thr(ifrom, ito, tid, inum, nthreads);
60     ThrData *thr = fix->get_thr(tid);
61     thr->timer(Timer::START);
62     ev_setup_thr(eflag, vflag, nall, eatom, vatom, cvatom, thr);
63 
64     if (inum > 0) {
65       if (evflag) {
66         if (eflag) {
67           if (force->newton_bond) eval<1,1,1>(ifrom, ito, thr);
68           else eval<1,1,0>(ifrom, ito, thr);
69         } else {
70           if (force->newton_bond) eval<1,0,1>(ifrom, ito, thr);
71           else eval<1,0,0>(ifrom, ito, thr);
72         }
73       } else {
74         if (force->newton_bond) eval<0,0,1>(ifrom, ito, thr);
75         else eval<0,0,0>(ifrom, ito, thr);
76       }
77     }
78     thr->timer(Timer::BOND);
79     reduce_thr(this, eflag, vflag, thr);
80   } // end of omp parallel region
81 }
82 
83 template <int EVFLAG, int EFLAG, int NEWTON_BOND>
eval(int nfrom,int nto,ThrData * const thr)84 void ImproperCossqOMP::eval(int nfrom, int nto, ThrData * const thr)
85 {
86   int i1,i2,i3,i4,n,type;
87   double vb1x,vb1y,vb1z,vb2x,vb2y,vb2z,vb3x,vb3y,vb3z;
88   double eimproper,f1[3],f2[3],f3[3],f4[3];
89   double rjisq, rji, rlksq, rlk, cosphi, angfac;
90   double cjiji, clkji, clklk, cfact1, cfact2, cfact3;
91 
92   eimproper = 0.0;
93 
94   const dbl3_t * _noalias const x = (dbl3_t *) atom->x[0];
95   dbl3_t * _noalias const f = (dbl3_t *) thr->get_f()[0];
96   const int5_t * _noalias const improperlist = (int5_t *) neighbor->improperlist[0];
97   const int nlocal = atom->nlocal;
98 
99   for (n = nfrom; n < nto; n++) {
100     i1 = improperlist[n].a;
101     i2 = improperlist[n].b;
102     i3 = improperlist[n].c;
103     i4 = improperlist[n].d;
104     type = improperlist[n].t;
105 
106     /* separation vector between i1 and i2, (i2-i1) */
107     vb1x = x[i2].x - x[i1].x;
108     vb1y = x[i2].y - x[i1].y;
109     vb1z = x[i2].z - x[i1].z;
110     rjisq = vb1x*vb1x + vb1y*vb1y + vb1z*vb1z ;
111     rji = sqrt(rjisq);
112 
113     /* separation vector between i2 and i3 (i3-i2) */
114     vb2x = x[i3].x - x[i2].x;
115     vb2y = x[i3].y - x[i2].y;
116     vb2z = x[i3].z - x[i2].z;
117 
118     /* separation vector between i3 and i4, (i4-i3) */
119     vb3x = x[i4].x - x[i3].x;
120     vb3y = x[i4].y - x[i3].y;
121     vb3z = x[i4].z - x[i3].z;
122     rlksq = vb3x*vb3x + vb3y*vb3y + vb3z*vb3z ;
123     rlk = sqrt(rlksq);
124 
125     cosphi = (vb3x*vb1x + vb3y*vb1y + vb3z*vb1z)/(rji * rlk);
126 
127     /* Check that cos(phi) is in the correct limits. */
128     if (cosphi > 1.0 + TOLERANCE || cosphi < (-1.0 - TOLERANCE))
129       problem(FLERR, i1, i2, i3, i4);
130 
131     /* Apply corrections to round-off errors. */
132     if (cosphi > 1.0)  cosphi -= SMALL;
133     if (cosphi < -1.0) cosphi += SMALL;
134 
135     /* Calculate the angle: */
136     double torangle = acos(cosphi);
137     cosphi = cos(torangle - chi[type]);
138 
139     if (EFLAG) eimproper = 0.5 * k[type] * cosphi * cosphi;
140 
141     /*
142       printf("The tags: %d-%d-%d-%d, of type %d .\n",atom->tag[i1],atom->tag[i2],atom->tag[i3],atom->tag[i4],type);
143       printf("The ji vector: %f, %f, %f.\nThe lk vector: %f, %f, %f.\n", vb1x,vb1y,vb1z,vb3x,vb3y,vb3z);
144       printf("The cosine of the angle: %-1.16e.\n", cosphi);
145       printf("The energy of the improper: %-1.16e with prefactor %-1.16e.\n", eimproper, 0.5*k[type]);
146     */
147 
148     /* Work out forces. */
149     angfac = - k[type] * cosphi;
150 
151     cjiji = rjisq;
152     clklk = rlksq;
153     /*CLKJI = RXLK * RXJI + RYLK * RYJI + RZLK * RZJI */
154     clkji = vb3x*vb1x + vb3y*vb1y + vb3z*vb1z;
155 
156     /*CFACT1 = CLKLK * CJIJI
157       CFACT1 = SQRT(CFACT1)
158       CFACT1 = ANGFAC / CFACT1*/
159     cfact1 = angfac / sqrt(clklk * cjiji);
160     /*CFACT2 = CLKJI / CLKLK*/
161     cfact2 = clkji / clklk;
162     /*CFACT3 = CLKJI / CJIJI*/
163     cfact3 = clkji / cjiji;
164 
165     /*FIX = -RXLK + CFACT3 * RXJI
166       FIY = -RYLK + CFACT3 * RYJI
167       FIZ = -RZLK + CFACT3 * RZJI*/
168     f1[0] = - vb3x + cfact3 * vb1x;
169     f1[1] = - vb3y + cfact3 * vb1y;
170     f1[2] = - vb3z + cfact3 * vb1z;
171 
172     /*FJX = -FIX
173       FJY = -FIY
174       FJZ = -FIZ*/
175     f2[0] = - f1[0];
176     f2[1] = - f1[1];
177     f2[2] = - f1[2];
178 
179     /*FKX = CFACT2 * RXLK - RXJI
180       FKY = CFACT2 * RYLK - RYJI
181       FKZ = CFACT2 * RZLK - RZJI*/
182     f3[0] = cfact2 * vb3x - vb1x;
183     f3[1] = cfact2 * vb3y - vb1y;
184     f3[2] = cfact2 * vb3z - vb1z;
185 
186     /*FLX = -FKX
187       FLY = -FKY
188       FLZ = -FKZ*/
189     f4[0] = - f3[0];
190     f4[1] = - f3[1];
191     f4[2] = - f3[2];
192 
193     /*FIX = FIX * CFACT1
194       FIY = FIY * CFACT1
195       FIZ = FIZ * CFACT1*/
196     f1[0] *= cfact1;
197     f1[1] *= cfact1;
198     f1[2] *= cfact1;
199 
200     /*FJX = FJX * CFACT1
201       FJY = FJY * CFACT1
202       FJZ = FJZ * CFACT1*/
203     f2[0] *= cfact1;
204     f2[1] *= cfact1;
205     f2[2] *= cfact1;
206 
207     /*FKX = FKX * CFACT1
208       FKY = FKY * CFACT1
209       FKZ = FKZ * CFACT1*/
210     f3[0] *= cfact1;
211     f3[1] *= cfact1;
212     f3[2] *= cfact1;
213 
214     /*FLX = FLX * CFACT1
215       FLY = FLY * CFACT1
216       FLZ = FLZ * CFACT1*/
217     f4[0] *= cfact1;
218     f4[1] *= cfact1;
219     f4[2] *= cfact1;
220 
221     /* Apply force to each of 4 atoms */
222     if (NEWTON_BOND || i1 < nlocal) {
223       f[i1].x += f1[0];
224       f[i1].y += f1[1];
225       f[i1].z += f1[2];
226     }
227 
228     if (NEWTON_BOND || i2 < nlocal) {
229       f[i2].x += f2[0];
230       f[i2].y += f2[1];
231       f[i2].z += f2[2];
232     }
233 
234     if (NEWTON_BOND || i3 < nlocal) {
235       f[i3].x += f3[0];
236       f[i3].y += f3[1];
237       f[i3].z += f3[2];
238     }
239 
240     if (NEWTON_BOND || i4 < nlocal) {
241       f[i4].x += f4[0];
242       f[i4].y += f4[1];
243       f[i4].z += f4[2];
244     }
245 
246     if (EVFLAG)
247       ev_tally_thr(this,i1,i2,i3,i4,nlocal,NEWTON_BOND,eimproper,f1,f3,f4,
248                      -vb1x,-vb1y,-vb1z,vb2x,vb2y,vb2z,vb3x,vb3y,vb3z,thr);
249   }
250 }
251