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 "dihedral_quadratic_omp.h"
20
21 #include "atom.h"
22 #include "comm.h"
23 #include "force.h"
24 #include "math_const.h"
25 #include "neighbor.h"
26
27 #include <cmath>
28
29 #include "omp_compat.h"
30 #include "suffix.h"
31 using namespace LAMMPS_NS;
32 using namespace MathConst;
33
34 #define TOLERANCE 0.05
35 #define SMALL 0.001
36 #define SMALLER 0.00001
37
38 /* ---------------------------------------------------------------------- */
39
DihedralQuadraticOMP(class LAMMPS * lmp)40 DihedralQuadraticOMP::DihedralQuadraticOMP(class LAMMPS *lmp)
41 : DihedralQuadratic(lmp), ThrOMP(lmp,THR_DIHEDRAL)
42 {
43 suffix_flag |= Suffix::OMP;
44 }
45
46 /* ---------------------------------------------------------------------- */
47
compute(int eflag,int vflag)48 void DihedralQuadraticOMP::compute(int eflag, int vflag)
49 {
50 ev_init(eflag,vflag);
51
52 const int nall = atom->nlocal + atom->nghost;
53 const int nthreads = comm->nthreads;
54 const int inum = neighbor->ndihedrallist;
55
56 #if defined(_OPENMP)
57 #pragma omp parallel LMP_DEFAULT_NONE LMP_SHARED(eflag,vflag)
58 #endif
59 {
60 int ifrom, ito, tid;
61
62 loop_setup_thr(ifrom, ito, tid, inum, nthreads);
63 ThrData *thr = fix->get_thr(tid);
64 thr->timer(Timer::START);
65 ev_setup_thr(eflag, vflag, nall, eatom, vatom, cvatom, thr);
66
67 if (inum > 0) {
68 if (evflag) {
69 if (eflag) {
70 if (force->newton_bond) eval<1,1,1>(ifrom, ito, thr);
71 else eval<1,1,0>(ifrom, ito, thr);
72 } else {
73 if (force->newton_bond) eval<1,0,1>(ifrom, ito, thr);
74 else eval<1,0,0>(ifrom, ito, thr);
75 }
76 } else {
77 if (force->newton_bond) eval<0,0,1>(ifrom, ito, thr);
78 else eval<0,0,0>(ifrom, ito, thr);
79 }
80 }
81 thr->timer(Timer::BOND);
82 reduce_thr(this, eflag, vflag, thr);
83 } // end of omp parallel region
84 }
85
86 template <int EVFLAG, int EFLAG, int NEWTON_BOND>
eval(int nfrom,int nto,ThrData * const thr)87 void DihedralQuadraticOMP::eval(int nfrom, int nto, ThrData * const thr)
88 {
89 int i1,i2,i3,i4,n,type;
90 double vb1x,vb1y,vb1z,vb2x,vb2y,vb2z,vb3x,vb3y,vb3z,vb2xm,vb2ym,vb2zm;
91 double edihedral,f1[3],f2[3],f3[3],f4[3];
92 double sb1,sb2,sb3,rb1,rb3,c0,b1mag2,b1mag,b2mag2;
93 double b2mag,b3mag2,b3mag,ctmp,r12c1,c1mag,r12c2;
94 double c2mag,sc1,sc2,s1,s12,c,p,pd,a,a11,a22;
95 double a33,a12,a13,a23,sx2,sy2,sz2;
96 double s2,cx,cy,cz,cmag,dx,phi,si,siinv,sin2;
97
98 edihedral = 0.0;
99
100 const dbl3_t * _noalias const x = (dbl3_t *) atom->x[0];
101 dbl3_t * _noalias const f = (dbl3_t *) thr->get_f()[0];
102 const int5_t * _noalias const dihedrallist = (int5_t *) neighbor->dihedrallist[0];
103 const int nlocal = atom->nlocal;
104
105 for (n = nfrom; n < nto; n++) {
106 i1 = dihedrallist[n].a;
107 i2 = dihedrallist[n].b;
108 i3 = dihedrallist[n].c;
109 i4 = dihedrallist[n].d;
110 type = dihedrallist[n].t;
111
112 // 1st bond
113
114 vb1x = x[i1].x - x[i2].x;
115 vb1y = x[i1].y - x[i2].y;
116 vb1z = x[i1].z - x[i2].z;
117
118 // 2nd bond
119
120 vb2x = x[i3].x - x[i2].x;
121 vb2y = x[i3].y - x[i2].y;
122 vb2z = x[i3].z - x[i2].z;
123
124 vb2xm = -vb2x;
125 vb2ym = -vb2y;
126 vb2zm = -vb2z;
127
128 // 3rd bond
129
130 vb3x = x[i4].x - x[i3].x;
131 vb3y = x[i4].y - x[i3].y;
132 vb3z = x[i4].z - x[i3].z;
133
134 // c0 calculation
135
136 sb1 = 1.0 / (vb1x*vb1x + vb1y*vb1y + vb1z*vb1z);
137 sb2 = 1.0 / (vb2x*vb2x + vb2y*vb2y + vb2z*vb2z);
138 sb3 = 1.0 / (vb3x*vb3x + vb3y*vb3y + vb3z*vb3z);
139
140 rb1 = sqrt(sb1);
141 rb3 = sqrt(sb3);
142
143 c0 = (vb1x*vb3x + vb1y*vb3y + vb1z*vb3z) * rb1*rb3;
144
145 // 1st and 2nd angle
146
147 b1mag2 = vb1x*vb1x + vb1y*vb1y + vb1z*vb1z;
148 b1mag = sqrt(b1mag2);
149 b2mag2 = vb2x*vb2x + vb2y*vb2y + vb2z*vb2z;
150 b2mag = sqrt(b2mag2);
151 b3mag2 = vb3x*vb3x + vb3y*vb3y + vb3z*vb3z;
152 b3mag = sqrt(b3mag2);
153
154 ctmp = vb1x*vb2x + vb1y*vb2y + vb1z*vb2z;
155 r12c1 = 1.0 / (b1mag*b2mag);
156 c1mag = ctmp * r12c1;
157
158 ctmp = vb2xm*vb3x + vb2ym*vb3y + vb2zm*vb3z;
159 r12c2 = 1.0 / (b2mag*b3mag);
160 c2mag = ctmp * r12c2;
161
162 // cos and sin of 2 angles and final c
163
164 sin2 = MAX(1.0 - c1mag*c1mag,0.0);
165 sc1 = sqrt(sin2);
166 if (sc1 < SMALL) sc1 = SMALL;
167 sc1 = 1.0/sc1;
168
169 sin2 = MAX(1.0 - c2mag*c2mag,0.0);
170 sc2 = sqrt(sin2);
171 if (sc2 < SMALL) sc2 = SMALL;
172 sc2 = 1.0/sc2;
173
174 s1 = sc1 * sc1;
175 s2 = sc2 * sc2;
176 s12 = sc1 * sc2;
177 c = (c0 + c1mag*c2mag) * s12;
178
179 cx = vb1y*vb2z - vb1z*vb2y;
180 cy = vb1z*vb2x - vb1x*vb2z;
181 cz = vb1x*vb2y - vb1y*vb2x;
182 cmag = sqrt(cx*cx + cy*cy + cz*cz);
183 dx = (cx*vb3x + cy*vb3y + cz*vb3z)/cmag/b3mag;
184
185 // error check
186
187 if (c > 1.0 + TOLERANCE || c < (-1.0 - TOLERANCE))
188 problem(FLERR, i1, i2, i3, i4);
189
190 if (c > 1.0) c = 1.0;
191 if (c < -1.0) c = -1.0;
192
193 // force & energy
194 // p = k ( phi- phi0)^2
195 // pd = dp/dc
196
197 phi = acos(c);
198 if (dx > 0.0) phi *= -1.0;
199 si = sin(phi);
200 if (fabs(si) < SMALLER) si = SMALLER;
201 siinv = 1.0/si;
202
203 double dphi = phi-phi0[type];
204 if (dphi > MY_PI) dphi -= 2*MY_PI;
205 else if (dphi < -MY_PI) dphi += 2*MY_PI;
206 p = k[type]*dphi;
207 pd = - 2.0 * p * siinv;
208 p = p * dphi;
209
210 if (EFLAG) edihedral = p;
211
212 a = pd;
213 c = c * a;
214 s12 = s12 * a;
215 a11 = c*sb1*s1;
216 a22 = -sb2 * (2.0*c0*s12 - c*(s1+s2));
217 a33 = c*sb3*s2;
218 a12 = -r12c1 * (c1mag*c*s1 + c2mag*s12);
219 a13 = -rb1*rb3*s12;
220 a23 = r12c2 * (c2mag*c*s2 + c1mag*s12);
221
222 sx2 = a12*vb1x + a22*vb2x + a23*vb3x;
223 sy2 = a12*vb1y + a22*vb2y + a23*vb3y;
224 sz2 = a12*vb1z + a22*vb2z + a23*vb3z;
225
226 f1[0] = a11*vb1x + a12*vb2x + a13*vb3x;
227 f1[1] = a11*vb1y + a12*vb2y + a13*vb3y;
228 f1[2] = a11*vb1z + a12*vb2z + a13*vb3z;
229
230 f2[0] = -sx2 - f1[0];
231 f2[1] = -sy2 - f1[1];
232 f2[2] = -sz2 - f1[2];
233
234 f4[0] = a13*vb1x + a23*vb2x + a33*vb3x;
235 f4[1] = a13*vb1y + a23*vb2y + a33*vb3y;
236 f4[2] = a13*vb1z + a23*vb2z + a33*vb3z;
237
238 f3[0] = sx2 - f4[0];
239 f3[1] = sy2 - f4[1];
240 f3[2] = sz2 - f4[2];
241
242 // apply force to each of 4 atoms
243
244 if (NEWTON_BOND || i1 < nlocal) {
245 f[i1].x += f1[0];
246 f[i1].y += f1[1];
247 f[i1].z += f1[2];
248 }
249
250 if (NEWTON_BOND || i2 < nlocal) {
251 f[i2].x += f2[0];
252 f[i2].y += f2[1];
253 f[i2].z += f2[2];
254 }
255
256 if (NEWTON_BOND || i3 < nlocal) {
257 f[i3].x += f3[0];
258 f[i3].y += f3[1];
259 f[i3].z += f3[2];
260 }
261
262 if (NEWTON_BOND || i4 < nlocal) {
263 f[i4].x += f4[0];
264 f[i4].y += f4[1];
265 f[i4].z += f4[2];
266 }
267
268 if (EVFLAG)
269 ev_tally_thr(this,i1,i2,i3,i4,nlocal,NEWTON_BOND,edihedral,f1,f3,f4,
270 vb1x,vb1y,vb1z,vb2x,vb2y,vb2z,vb3x,vb3y,vb3z,thr);
271 }
272 }
273