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41 #include "gromacs/gmxlib/nrnb.h"
42 #include "gromacs/math/functions.h"
43 #include "gromacs/math/vec.h"
44 #include "gromacs/mdlib/constr.h"
45 #include "gromacs/mdtypes/inputrec.h"
46 #include "gromacs/mdtypes/md_enums.h"
47 #include "gromacs/utility/smalloc.h"
49 typedef struct gmx_shakedata
52 real *half_of_reduced_mass;
53 real *distance_squared_tolerance;
54 real *constraint_distance_squared;
62 gmx_shakedata_t shake_init()
70 d->half_of_reduced_mass = NULL;
71 d->distance_squared_tolerance = NULL;
72 d->constraint_distance_squared = NULL;
74 /* SOR initialization */
82 /*! \brief Inner kernel for SHAKE constraints
84 * Original implementation from R.C. van Schaik and W.F. van Gunsteren
85 * (ETH Zuerich, June 1992), adapted for GROMACS by David van der
86 * Spoel November 1992.
88 * The algorithm here is based section five of Ryckaert, Ciccotti and
89 * Berendsen, J Comp Phys, 23, 327, 1977.
91 * \param[in] iatom Mini-topology of triples of constraint type (unused in this
92 * function) and indices of the two atoms involved
93 * \param[in] ncon Number of constraints
94 * \param[out] nnit Number of iterations performed
95 * \param[in] maxnit Maximum number of iterations permitted
96 * \param[in] constraint_distance_squared The objective value for each constraint
97 * \param[inout] positions The initial (and final) values of the positions of all atoms
98 * \param[in] initial_displacements The initial displacements of each constraint
99 * \param[in] half_of_reduced_mass Half of the reduced mass for each constraint
100 * \param[in] omega SHAKE over-relaxation factor (set non-1.0 by
101 * using shake-sor=yes in the .mdp, but there is no documentation anywhere)
102 * \param[in] invmass Inverse mass of each atom
103 * \param[in] distance_squared_tolerance Multiplicative tolerance on the difference in the
104 * square of the constrained distance (see code)
105 * \param[out] scaled_lagrange_multiplier Scaled Lagrange multiplier for each constraint (-2 * eta from p. 336
106 * of the paper, divided by the constraint distance)
107 * \param[out] nerror Zero upon success, returns one more than the index of the
108 * problematic constraint if the input was malformed
110 * \todo Make SHAKE use better data structures, in particular for iatom. */
111 void cshake(const int iatom[], int ncon, int *nnit, int maxnit,
112 const real constraint_distance_squared[], real positions[],
113 const real initial_displacements[], const real half_of_reduced_mass[], real omega,
114 const real invmass[], const real distance_squared_tolerance[],
115 real scaled_lagrange_multiplier[], int *nerror)
117 /* default should be increased! MRS 8/4/2009 */
118 const real mytol = 1e-10;
120 int ll, i, j, i3, j3, l3;
121 int ix, iy, iz, jx, jy, jz;
123 real constraint_distance_squared_ll;
124 real r_prime_squared;
125 real scaled_lagrange_multiplier_ll;
126 real r_prime_x, r_prime_y, r_prime_z, diff, im, jm;
127 real xh, yh, zh, rijx, rijy, rijz;
128 int nit, error, nconv;
131 // TODO nconv is used solely as a boolean, so we should write the
135 for (nit = 0; (nit < maxnit) && (nconv != 0) && (error == 0); nit++)
138 for (ll = 0; (ll < ncon) && (error == 0); ll++)
141 rijx = initial_displacements[l3+XX];
142 rijy = initial_displacements[l3+YY];
143 rijz = initial_displacements[l3+ZZ];
155 /* Compute r prime between atoms i and j, which is the
156 displacement *before* this update stage */
157 r_prime_x = positions[ix]-positions[jx];
158 r_prime_y = positions[iy]-positions[jy];
159 r_prime_z = positions[iz]-positions[jz];
160 r_prime_squared = (r_prime_x * r_prime_x +
161 r_prime_y * r_prime_y +
162 r_prime_z * r_prime_z);
163 constraint_distance_squared_ll = constraint_distance_squared[ll];
164 diff = constraint_distance_squared_ll - r_prime_squared;
166 /* iconvf is less than 1 when the error is smaller than a bound */
167 iconvf = fabs(diff) * distance_squared_tolerance[ll];
171 nconv = static_cast<int>(iconvf);
172 r_dot_r_prime = (rijx * r_prime_x +
176 if (r_dot_r_prime < constraint_distance_squared_ll * mytol)
182 /* The next line solves equation 5.6 (neglecting
183 the term in g^2), for g */
184 scaled_lagrange_multiplier_ll = omega*diff*half_of_reduced_mass[ll]/r_dot_r_prime;
185 scaled_lagrange_multiplier[ll] += scaled_lagrange_multiplier_ll;
186 xh = rijx * scaled_lagrange_multiplier_ll;
187 yh = rijy * scaled_lagrange_multiplier_ll;
188 zh = rijz * scaled_lagrange_multiplier_ll;
191 positions[ix] += xh*im;
192 positions[iy] += yh*im;
193 positions[iz] += zh*im;
194 positions[jx] -= xh*jm;
195 positions[jy] -= yh*jm;
196 positions[jz] -= zh*jm;
205 int vec_shakef(FILE *fplog, gmx_shakedata_t shaked,
206 real invmass[], int ncon,
207 t_iparams ip[], t_iatom *iatom,
208 real tol, rvec x[], rvec prime[], real omega,
209 gmx_bool bFEP, real lambda, real scaled_lagrange_multiplier[],
211 gmx_bool bCalcVir, tensor vir_r_m_dr, int econq)
214 real *half_of_reduced_mass, *distance_squared_tolerance, *constraint_distance_squared;
216 int nit = 0, ll, i, j, d, d2, type;
221 real constraint_distance;
223 if (ncon > shaked->nalloc)
225 shaked->nalloc = over_alloc_dd(ncon);
226 srenew(shaked->rij, shaked->nalloc);
227 srenew(shaked->half_of_reduced_mass, shaked->nalloc);
228 srenew(shaked->distance_squared_tolerance, shaked->nalloc);
229 srenew(shaked->constraint_distance_squared, shaked->nalloc);
232 half_of_reduced_mass = shaked->half_of_reduced_mass;
233 distance_squared_tolerance = shaked->distance_squared_tolerance;
234 constraint_distance_squared = shaked->constraint_distance_squared;
238 for (ll = 0; (ll < ncon); ll++, ia += 3)
244 mm = 2.0*(invmass[i]+invmass[j]);
245 rij[ll][XX] = x[i][XX]-x[j][XX];
246 rij[ll][YY] = x[i][YY]-x[j][YY];
247 rij[ll][ZZ] = x[i][ZZ]-x[j][ZZ];
248 half_of_reduced_mass[ll] = 1.0/mm;
251 constraint_distance = L1*ip[type].constr.dA + lambda*ip[type].constr.dB;
255 constraint_distance = ip[type].constr.dA;
257 constraint_distance_squared[ll] = gmx::square(constraint_distance);
258 distance_squared_tolerance[ll] = 0.5/(constraint_distance_squared[ll]*tol);
264 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);
267 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);
275 fprintf(fplog, "Shake did not converge in %d steps\n", maxnit);
277 fprintf(stderr, "Shake did not converge in %d steps\n", maxnit);
284 fprintf(fplog, "Inner product between old and new vector <= 0.0!\n"
285 "constraint #%d atoms %d and %d\n",
286 error-1, iatom[3*(error-1)+1]+1, iatom[3*(error-1)+2]+1);
288 fprintf(stderr, "Inner product between old and new vector <= 0.0!\n"
289 "constraint #%d atoms %d and %d\n",
290 error-1, iatom[3*(error-1)+1]+1, iatom[3*(error-1)+2]+1);
294 /* Constraint virial and correct the Lagrange multipliers for the length */
298 for (ll = 0; (ll < ncon); ll++, ia += 3)
304 if ((econq == econqCoord) && v != NULL)
306 /* Correct the velocities */
307 mm = scaled_lagrange_multiplier[ll]*invmass[i]*invdt;
308 for (d = 0; d < DIM; d++)
310 v[ia[1]][d] += mm*rij[ll][d];
312 mm = scaled_lagrange_multiplier[ll]*invmass[j]*invdt;
313 for (d = 0; d < DIM; d++)
315 v[ia[2]][d] -= mm*rij[ll][d];
320 /* constraint virial */
323 mm = scaled_lagrange_multiplier[ll];
324 for (d = 0; d < DIM; d++)
327 for (d2 = 0; d2 < DIM; d2++)
329 vir_r_m_dr[d][d2] -= tmp*rij[ll][d2];
335 /* cshake and crattle produce Lagrange multipliers scaled by
336 the reciprocal of the constraint length, so fix that */
339 constraint_distance = L1*ip[type].constr.dA + lambda*ip[type].constr.dB;
343 constraint_distance = ip[type].constr.dA;
345 scaled_lagrange_multiplier[ll] *= constraint_distance;
351 static void check_cons(FILE *log, int nc, rvec x[], rvec prime[], rvec v[],
352 t_iparams ip[], t_iatom *iatom,
353 real invmass[], int econq)
362 " i mi j mj before after should be\n");
364 for (i = 0; (i < nc); i++, ia += 3)
368 rvec_sub(x[ai], x[aj], dx);
374 rvec_sub(prime[ai], prime[aj], dx);
376 fprintf(log, "%5d %5.2f %5d %5.2f %10.5f %10.5f %10.5f\n",
377 ai+1, 1.0/invmass[ai],
378 aj+1, 1.0/invmass[aj], d, dp, ip[ia[0]].constr.dA);
381 rvec_sub(v[ai], v[aj], dv);
383 rvec_sub(prime[ai], prime[aj], dv);
385 fprintf(log, "%5d %5.2f %5d %5.2f %10.5f %10.5f %10.5f\n",
386 ai+1, 1.0/invmass[ai],
387 aj+1, 1.0/invmass[aj], d, dp, 0.);
393 gmx_bool bshakef(FILE *log, gmx_shakedata_t shaked,
394 real invmass[], int nblocks, int sblock[],
395 t_idef *idef, t_inputrec *ir, rvec x_s[], rvec prime[],
396 t_nrnb *nrnb, real *scaled_lagrange_multiplier, real lambda, real *dvdlambda,
397 real invdt, rvec *v, gmx_bool bCalcVir, tensor vir_r_m_dr,
398 gmx_bool bDumpOnError, int econq)
402 int i, n0, ncon, blen, type, ll;
403 int tnit = 0, trij = 0;
406 fprintf(log, "nblocks=%d, sblock[0]=%d\n", nblocks, sblock[0]);
409 ncon = idef->il[F_CONSTR].nr/3;
411 for (ll = 0; ll < ncon; ll++)
413 scaled_lagrange_multiplier[ll] = 0;
416 iatoms = &(idef->il[F_CONSTR].iatoms[sblock[0]]);
417 for (i = 0; (i < nblocks); )
419 blen = (sblock[i+1]-sblock[i]);
421 n0 = vec_shakef(log, shaked, invmass, blen, idef->iparams,
422 iatoms, ir->shake_tol, x_s, prime, shaked->omega,
423 ir->efep != efepNO, lambda, scaled_lagrange_multiplier, invdt, v, bCalcVir, vir_r_m_dr,
427 check_cons(log, blen, x_s, prime, v, idef->iparams, iatoms, invmass, econq);
432 if (bDumpOnError && log)
435 check_cons(log, blen, x_s, prime, v, idef->iparams, iatoms, invmass, econq);
442 iatoms += 3*blen; /* Increment pointer! */
443 scaled_lagrange_multiplier += blen;
446 /* only for position part? */
447 if (econq == econqCoord)
449 if (ir->efep != efepNO)
452 /* TODO This should probably use invdt, so that sd integrator scaling works properly */
453 dt_2 = 1/gmx::square(ir->delta_t);
455 for (ll = 0; ll < ncon; ll++)
457 type = idef->il[F_CONSTR].iatoms[3*ll];
459 /* Per equations in the manual, dv/dl = -2 \sum_ll lagrangian_ll * r_ll * (d_B - d_A) */
460 /* The vector scaled_lagrange_multiplier[ll] contains the value -2 r_ll eta_ll (eta_ll is the
461 estimate of the Langrangian, definition on page 336 of Ryckaert et al 1977),
462 so the pre-factors are already present. */
463 bondA = idef->iparams[type].constr.dA;
464 bondB = idef->iparams[type].constr.dB;
465 dvdl += scaled_lagrange_multiplier[ll] * dt_2 * (bondB - bondA);
471 fprintf(log, "tnit: %5d omega: %10.5f\n", tnit, omega);
475 if (tnit > shaked->gamma)
477 shaked->delta *= -0.5;
479 shaked->omega += shaked->delta;
480 shaked->gamma = tnit;
482 inc_nrnb(nrnb, eNR_SHAKE, tnit);
483 inc_nrnb(nrnb, eNR_SHAKE_RIJ, trij);
486 inc_nrnb(nrnb, eNR_CONSTR_V, trij*2);
490 inc_nrnb(nrnb, eNR_CONSTR_VIR, trij);
496 void crattle(int iatom[], int ncon, int *nnit, int maxnit,
497 real constraint_distance_squared[], real vp[], real rij[], real m2[], real omega,
498 real invmass[], real distance_squared_tolerance[], real scaled_lagrange_multiplier[],
499 int *nerror, real invdt)
502 * r.c. van schaik and w.f. van gunsteren
505 * Adapted for use with Gromacs by David van der Spoel november 92 and later.
506 * rattle added by M.R. Shirts, April 2004, from code written by Jay Ponder in TINKER
507 * second part of rattle algorithm
510 int ll, i, j, i3, j3, l3;
511 int ix, iy, iz, jx, jy, jz;
512 real constraint_distance_squared_ll;
513 real vpijd, vx, vy, vz, acor, fac, im, jm;
514 real xh, yh, zh, rijx, rijy, rijz;
515 int nit, error, nconv;
518 // TODO nconv is used solely as a boolean, so we should write the
522 for (nit = 0; (nit < maxnit) && (nconv != 0) && (error == 0); nit++)
525 for (ll = 0; (ll < ncon) && (error == 0); ll++)
545 vpijd = vx*rijx+vy*rijy+vz*rijz;
546 constraint_distance_squared_ll = constraint_distance_squared[ll];
548 /* iconv is zero when the error is smaller than a bound */
549 iconvf = fabs(vpijd)*(distance_squared_tolerance[ll]/invdt);
553 nconv = static_cast<int>(iconvf);
554 fac = omega*2.0*m2[ll]/constraint_distance_squared_ll;
556 scaled_lagrange_multiplier[ll] += acor;