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43 #include "gromacs/gmxlib/nrnb.h"
44 #include "gromacs/math/functions.h"
45 #include "gromacs/math/vec.h"
46 #include "gromacs/mdtypes/inputrec.h"
47 #include "gromacs/mdtypes/md_enums.h"
48 #include "gromacs/utility/smalloc.h"
50 typedef struct gmx_shakedata
53 real *half_of_reduced_mass;
54 real *distance_squared_tolerance;
55 real *constraint_distance_squared;
63 gmx_shakedata_t shake_init()
71 d->half_of_reduced_mass = nullptr;
72 d->distance_squared_tolerance = nullptr;
73 d->constraint_distance_squared = nullptr;
75 /* SOR initialization */
83 /*! \brief Inner kernel for SHAKE constraints
85 * Original implementation from R.C. van Schaik and W.F. van Gunsteren
86 * (ETH Zuerich, June 1992), adapted for GROMACS by David van der
87 * Spoel November 1992.
89 * The algorithm here is based section five of Ryckaert, Ciccotti and
90 * Berendsen, J Comp Phys, 23, 327, 1977.
92 * \param[in] iatom Mini-topology of triples of constraint type (unused in this
93 * function) and indices of the two atoms involved
94 * \param[in] ncon Number of constraints
95 * \param[out] nnit Number of iterations performed
96 * \param[in] maxnit Maximum number of iterations permitted
97 * \param[in] constraint_distance_squared The objective value for each constraint
98 * \param[inout] positions The initial (and final) values of the positions of all atoms
99 * \param[in] initial_displacements The initial displacements of each constraint
100 * \param[in] half_of_reduced_mass Half of the reduced mass for each constraint
101 * \param[in] omega SHAKE over-relaxation factor (set non-1.0 by
102 * using shake-sor=yes in the .mdp, but there is no documentation anywhere)
103 * \param[in] invmass Inverse mass of each atom
104 * \param[in] distance_squared_tolerance Multiplicative tolerance on the difference in the
105 * square of the constrained distance (see code)
106 * \param[out] scaled_lagrange_multiplier Scaled Lagrange multiplier for each constraint (-2 * eta from p. 336
107 * of the paper, divided by the constraint distance)
108 * \param[out] nerror Zero upon success, returns one more than the index of the
109 * problematic constraint if the input was malformed
111 * \todo Make SHAKE use better data structures, in particular for iatom. */
112 void cshake(const int iatom[], int ncon, int *nnit, int maxnit,
113 const real constraint_distance_squared[], real positions[],
114 const real initial_displacements[], const real half_of_reduced_mass[], real omega,
115 const real invmass[], const real distance_squared_tolerance[],
116 real scaled_lagrange_multiplier[], int *nerror)
118 /* default should be increased! MRS 8/4/2009 */
119 const real mytol = 1e-10;
121 int ll, i, j, i3, j3, l3;
122 int ix, iy, iz, jx, jy, jz;
124 real constraint_distance_squared_ll;
125 real r_prime_squared;
126 real scaled_lagrange_multiplier_ll;
127 real r_prime_x, r_prime_y, r_prime_z, diff, im, jm;
128 real xh, yh, zh, rijx, rijy, rijz;
129 int nit, error, nconv;
132 // TODO nconv is used solely as a boolean, so we should write the
136 for (nit = 0; (nit < maxnit) && (nconv != 0) && (error == 0); nit++)
139 for (ll = 0; (ll < ncon) && (error == 0); ll++)
142 rijx = initial_displacements[l3+XX];
143 rijy = initial_displacements[l3+YY];
144 rijz = initial_displacements[l3+ZZ];
156 /* Compute r prime between atoms i and j, which is the
157 displacement *before* this update stage */
158 r_prime_x = positions[ix]-positions[jx];
159 r_prime_y = positions[iy]-positions[jy];
160 r_prime_z = positions[iz]-positions[jz];
161 r_prime_squared = (r_prime_x * r_prime_x +
162 r_prime_y * r_prime_y +
163 r_prime_z * r_prime_z);
164 constraint_distance_squared_ll = constraint_distance_squared[ll];
165 diff = constraint_distance_squared_ll - r_prime_squared;
167 /* iconvf is less than 1 when the error is smaller than a bound */
168 iconvf = fabs(diff) * distance_squared_tolerance[ll];
172 nconv = static_cast<int>(iconvf);
173 r_dot_r_prime = (rijx * r_prime_x +
177 if (r_dot_r_prime < constraint_distance_squared_ll * mytol)
183 /* The next line solves equation 5.6 (neglecting
184 the term in g^2), for g */
185 scaled_lagrange_multiplier_ll = omega*diff*half_of_reduced_mass[ll]/r_dot_r_prime;
186 scaled_lagrange_multiplier[ll] += scaled_lagrange_multiplier_ll;
187 xh = rijx * scaled_lagrange_multiplier_ll;
188 yh = rijy * scaled_lagrange_multiplier_ll;
189 zh = rijz * scaled_lagrange_multiplier_ll;
192 positions[ix] += xh*im;
193 positions[iy] += yh*im;
194 positions[iz] += zh*im;
195 positions[jx] -= xh*jm;
196 positions[jy] -= yh*jm;
197 positions[jz] -= zh*jm;
207 crattle(int iatom[], int ncon, int *nnit, int maxnit,
208 real constraint_distance_squared[], real vp[], real rij[], real m2[], real omega,
209 real invmass[], real distance_squared_tolerance[], real scaled_lagrange_multiplier[],
210 int *nerror, real invdt)
213 * r.c. van schaik and w.f. van gunsteren
216 * Adapted for use with Gromacs by David van der Spoel november 92 and later.
217 * rattle added by M.R. Shirts, April 2004, from code written by Jay Ponder in TINKER
218 * second part of rattle algorithm
221 int ll, i, j, i3, j3, l3;
222 int ix, iy, iz, jx, jy, jz;
223 real constraint_distance_squared_ll;
224 real vpijd, vx, vy, vz, acor, fac, im, jm;
225 real xh, yh, zh, rijx, rijy, rijz;
226 int nit, error, nconv;
229 // TODO nconv is used solely as a boolean, so we should write the
233 for (nit = 0; (nit < maxnit) && (nconv != 0) && (error == 0); nit++)
236 for (ll = 0; (ll < ncon) && (error == 0); ll++)
256 vpijd = vx*rijx+vy*rijy+vz*rijz;
257 constraint_distance_squared_ll = constraint_distance_squared[ll];
259 /* iconv is zero when the error is smaller than a bound */
260 iconvf = fabs(vpijd)*(distance_squared_tolerance[ll]/invdt);
264 nconv = static_cast<int>(iconvf);
265 fac = omega*2.0*m2[ll]/constraint_distance_squared_ll;
267 scaled_lagrange_multiplier[ll] += acor;
288 static int vec_shakef(FILE *fplog, gmx_shakedata_t shaked,
289 real invmass[], int ncon,
290 t_iparams ip[], t_iatom *iatom,
291 real tol, rvec x[], rvec prime[], real omega,
292 gmx_bool bFEP, real lambda, real scaled_lagrange_multiplier[],
294 gmx_bool bCalcVir, tensor vir_r_m_dr, int econq)
297 real *half_of_reduced_mass, *distance_squared_tolerance, *constraint_distance_squared;
299 int nit = 0, ll, i, j, d, d2, type;
304 real constraint_distance;
306 if (ncon > shaked->nalloc)
308 shaked->nalloc = over_alloc_dd(ncon);
309 srenew(shaked->rij, shaked->nalloc);
310 srenew(shaked->half_of_reduced_mass, shaked->nalloc);
311 srenew(shaked->distance_squared_tolerance, shaked->nalloc);
312 srenew(shaked->constraint_distance_squared, shaked->nalloc);
315 half_of_reduced_mass = shaked->half_of_reduced_mass;
316 distance_squared_tolerance = shaked->distance_squared_tolerance;
317 constraint_distance_squared = shaked->constraint_distance_squared;
321 for (ll = 0; (ll < ncon); ll++, ia += 3)
327 mm = 2.0*(invmass[i]+invmass[j]);
328 rij[ll][XX] = x[i][XX]-x[j][XX];
329 rij[ll][YY] = x[i][YY]-x[j][YY];
330 rij[ll][ZZ] = x[i][ZZ]-x[j][ZZ];
331 half_of_reduced_mass[ll] = 1.0/mm;
334 constraint_distance = L1*ip[type].constr.dA + lambda*ip[type].constr.dB;
338 constraint_distance = ip[type].constr.dA;
340 constraint_distance_squared[ll] = gmx::square(constraint_distance);
341 distance_squared_tolerance[ll] = 0.5/(constraint_distance_squared[ll]*tol);
347 cshake(iatom, ncon, &nit, maxnit, constraint_distance_squared, prime[0], rij[0], half_of_reduced_mass, omega, invmass, distance_squared_tolerance, scaled_lagrange_multiplier, &error);
350 crattle(iatom, ncon, &nit, maxnit, constraint_distance_squared, prime[0], rij[0], half_of_reduced_mass, omega, invmass, distance_squared_tolerance, scaled_lagrange_multiplier, &error, invdt);
358 fprintf(fplog, "Shake did not converge in %d steps\n", maxnit);
360 fprintf(stderr, "Shake did not converge in %d steps\n", maxnit);
367 fprintf(fplog, "Inner product between old and new vector <= 0.0!\n"
368 "constraint #%d atoms %d and %d\n",
369 error-1, iatom[3*(error-1)+1]+1, iatom[3*(error-1)+2]+1);
371 fprintf(stderr, "Inner product between old and new vector <= 0.0!\n"
372 "constraint #%d atoms %d and %d\n",
373 error-1, iatom[3*(error-1)+1]+1, iatom[3*(error-1)+2]+1);
377 /* Constraint virial and correct the Lagrange multipliers for the length */
381 for (ll = 0; (ll < ncon); ll++, ia += 3)
387 if ((econq == econqCoord) && v != nullptr)
389 /* Correct the velocities */
390 mm = scaled_lagrange_multiplier[ll]*invmass[i]*invdt;
391 for (d = 0; d < DIM; d++)
393 v[ia[1]][d] += mm*rij[ll][d];
395 mm = scaled_lagrange_multiplier[ll]*invmass[j]*invdt;
396 for (d = 0; d < DIM; d++)
398 v[ia[2]][d] -= mm*rij[ll][d];
403 /* constraint virial */
406 mm = scaled_lagrange_multiplier[ll];
407 for (d = 0; d < DIM; d++)
410 for (d2 = 0; d2 < DIM; d2++)
412 vir_r_m_dr[d][d2] -= tmp*rij[ll][d2];
418 /* cshake and crattle produce Lagrange multipliers scaled by
419 the reciprocal of the constraint length, so fix that */
422 constraint_distance = L1*ip[type].constr.dA + lambda*ip[type].constr.dB;
426 constraint_distance = ip[type].constr.dA;
428 scaled_lagrange_multiplier[ll] *= constraint_distance;
434 static void check_cons(FILE *log, int nc, rvec x[], rvec prime[], rvec v[],
435 t_iparams ip[], t_iatom *iatom,
436 real invmass[], int econq)
445 " i mi j mj before after should be\n");
447 for (i = 0; (i < nc); i++, ia += 3)
451 rvec_sub(x[ai], x[aj], dx);
457 rvec_sub(prime[ai], prime[aj], dx);
459 fprintf(log, "%5d %5.2f %5d %5.2f %10.5f %10.5f %10.5f\n",
460 ai+1, 1.0/invmass[ai],
461 aj+1, 1.0/invmass[aj], d, dp, ip[ia[0]].constr.dA);
464 rvec_sub(v[ai], v[aj], dv);
466 rvec_sub(prime[ai], prime[aj], dv);
468 fprintf(log, "%5d %5.2f %5d %5.2f %10.5f %10.5f %10.5f\n",
469 ai+1, 1.0/invmass[ai],
470 aj+1, 1.0/invmass[aj], d, dp, 0.);
476 gmx_bool bshakef(FILE *log, gmx_shakedata_t shaked,
477 real invmass[], int nblocks, int sblock[],
478 t_idef *idef, t_inputrec *ir, rvec x_s[], rvec prime[],
479 t_nrnb *nrnb, real * const scaled_lagrange_multiplier, real lambda, real *dvdlambda,
480 real invdt, rvec *v, gmx_bool bCalcVir, tensor vir_r_m_dr,
481 gmx_bool bDumpOnError, int econq)
484 real *lam, dt_2, dvdl;
485 int i, n0, ncon, blen, type, ll;
486 int tnit = 0, trij = 0;
489 fprintf(log, "nblocks=%d, sblock[0]=%d\n", nblocks, sblock[0]);
492 ncon = idef->il[F_CONSTR].nr/3;
494 for (ll = 0; ll < ncon; ll++)
496 scaled_lagrange_multiplier[ll] = 0;
499 // TODO Rewrite this block so that it is obvious that i, iatoms
500 // and lam are all iteration variables. Is this easier if the
501 // sblock data structure is organized differently?
502 iatoms = &(idef->il[F_CONSTR].iatoms[sblock[0]]);
503 lam = scaled_lagrange_multiplier;
504 for (i = 0; (i < nblocks); )
506 blen = (sblock[i+1]-sblock[i]);
508 n0 = vec_shakef(log, shaked, invmass, blen, idef->iparams,
509 iatoms, ir->shake_tol, x_s, prime, shaked->omega,
510 ir->efep != efepNO, lambda, scaled_lagrange_multiplier, invdt, v, bCalcVir, vir_r_m_dr,
514 check_cons(log, blen, x_s, prime, v, idef->iparams, iatoms, invmass, econq);
519 if (bDumpOnError && log)
522 check_cons(log, blen, x_s, prime, v, idef->iparams, iatoms, invmass, econq);
529 iatoms += 3*blen; /* Increment pointer! */
533 /* only for position part? */
534 if (econq == econqCoord)
536 if (ir->efep != efepNO)
539 /* TODO This should probably use invdt, so that sd integrator scaling works properly */
540 dt_2 = 1/gmx::square(ir->delta_t);
542 for (ll = 0; ll < ncon; ll++)
544 type = idef->il[F_CONSTR].iatoms[3*ll];
546 /* Per equations in the manual, dv/dl = -2 \sum_ll lagrangian_ll * r_ll * (d_B - d_A) */
547 /* The vector scaled_lagrange_multiplier[ll] contains the value -2 r_ll eta_ll (eta_ll is the
548 estimate of the Langrangian, definition on page 336 of Ryckaert et al 1977),
549 so the pre-factors are already present. */
550 bondA = idef->iparams[type].constr.dA;
551 bondB = idef->iparams[type].constr.dB;
552 dvdl += scaled_lagrange_multiplier[ll] * dt_2 * (bondB - bondA);
558 fprintf(log, "tnit: %5d omega: %10.5f\n", tnit, omega);
562 if (tnit > shaked->gamma)
564 shaked->delta *= -0.5;
566 shaked->omega += shaked->delta;
567 shaked->gamma = tnit;
569 inc_nrnb(nrnb, eNR_SHAKE, tnit);
570 inc_nrnb(nrnb, eNR_SHAKE_RIJ, trij);
573 inc_nrnb(nrnb, eNR_CONSTR_V, trij*2);
577 inc_nrnb(nrnb, eNR_CONSTR_VIR, trij);