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44 #include "gromacs/random/random.h"
45 #include "gromacs/utility/smalloc.h"
46 #include "gromacs/math/units.h"
49 #include "gromacs/math/vec.h"
53 #include "gromacs/random/random.h"
55 #define PROBABILITYCUTOFF 100
56 /* we don't bother evaluating if events are more rare than exp(-100) = 3.7x10^-44 */
59 ereTEMP, ereLAMBDA, ereENDSINGLE, ereTL, ereNR
61 const char *erename[ereNR] = { "temperature", "lambda", "end_single_marker", "temperature and lambda"};
62 /* end_single_marker merely notes the end of single variable replica exchange. All types higher than
63 it are multiple replica exchange methods */
64 /* Eventually, should add 'pressure', 'temperature and pressure', 'lambda_and_pressure', 'temperature_lambda_pressure'?;
65 Let's wait until we feel better about the pressure control methods giving exact ensembles. Right now, we assume constant pressure */
67 typedef struct gmx_repl_ex
87 /* these are helper arrays for replica exchange; allocated here so they
88 don't have to be allocated each time */
96 /* helper arrays to hold the quantities that are exchanged */
105 static gmx_bool repl_quantity(const gmx_multisim_t *ms,
106 struct gmx_repl_ex *re, int ere, real q)
112 snew(qall, ms->nsim);
114 gmx_sum_sim(ms->nsim, qall, ms);
117 for (s = 1; s < ms->nsim; s++)
119 if (qall[s] != qall[0])
127 /* Set the replica exchange type and quantities */
130 snew(re->q[ere], re->nrepl);
131 for (s = 0; s < ms->nsim; s++)
133 re->q[ere][s] = qall[s];
140 gmx_repl_ex_t init_replica_exchange(FILE *fplog,
141 const gmx_multisim_t *ms,
142 const t_state *state,
143 const t_inputrec *ir,
144 int nst, int nex, int init_seed)
148 struct gmx_repl_ex *re;
150 gmx_bool bLambda = FALSE;
152 fprintf(fplog, "\nInitializing Replica Exchange\n");
154 if (ms == NULL || ms->nsim == 1)
156 gmx_fatal(FARGS, "Nothing to exchange with only one replica, maybe you forgot to set the -multi option of mdrun?");
158 if (!EI_DYNAMICS(ir->eI))
160 gmx_fatal(FARGS, "Replica exchange is only supported by dynamical simulations");
161 /* Note that PAR(cr) is defined by cr->nnodes > 1, which is
162 * distinct from MULTISIM(cr). A multi-simulation only runs
163 * with real MPI parallelism, but this does not imply PAR(cr)
166 * Since we are using a dynamical integrator, the only
167 * decomposition is DD, so PAR(cr) and DOMAINDECOMP(cr) are
168 * synonymous. The only way for cr->nnodes > 1 to be true is
169 * if we are using DD. */
175 re->nrepl = ms->nsim;
176 snew(re->q, ereENDSINGLE);
178 fprintf(fplog, "Repl There are %d replicas:\n", re->nrepl);
180 check_multi_int(fplog, ms, state->natoms, "the number of atoms", FALSE);
181 check_multi_int(fplog, ms, ir->eI, "the integrator", FALSE);
182 check_multi_int64(fplog, ms, ir->init_step+ir->nsteps, "init_step+nsteps", FALSE);
183 check_multi_int64(fplog, ms, (ir->init_step+nst-1)/nst,
184 "first exchange step: init_step/-replex", FALSE);
185 check_multi_int(fplog, ms, ir->etc, "the temperature coupling", FALSE);
186 check_multi_int(fplog, ms, ir->opts.ngtc,
187 "the number of temperature coupling groups", FALSE);
188 check_multi_int(fplog, ms, ir->epc, "the pressure coupling", FALSE);
189 check_multi_int(fplog, ms, ir->efep, "free energy", FALSE);
190 check_multi_int(fplog, ms, ir->fepvals->n_lambda, "number of lambda states", FALSE);
192 re->temp = ir->opts.ref_t[0];
193 for (i = 1; (i < ir->opts.ngtc); i++)
195 if (ir->opts.ref_t[i] != re->temp)
197 fprintf(fplog, "\nWARNING: The temperatures of the different temperature coupling groups are not identical\n\n");
198 fprintf(stderr, "\nWARNING: The temperatures of the different temperature coupling groups are not identical\n\n");
203 bTemp = repl_quantity(ms, re, ereTEMP, re->temp);
204 if (ir->efep != efepNO)
206 bLambda = repl_quantity(ms, re, ereLAMBDA, (real)ir->fepvals->init_fep_state);
208 if (re->type == -1) /* nothing was assigned */
210 gmx_fatal(FARGS, "The properties of the %d systems are all the same, there is nothing to exchange", re->nrepl);
212 if (bLambda && bTemp)
219 please_cite(fplog, "Sugita1999a");
220 if (ir->epc != epcNO)
223 fprintf(fplog, "Repl Using Constant Pressure REMD.\n");
224 please_cite(fplog, "Okabe2001a");
226 if (ir->etc == etcBERENDSEN)
228 gmx_fatal(FARGS, "REMD with the %s thermostat does not produce correct potential energy distributions, consider using the %s thermostat instead",
229 ETCOUPLTYPE(ir->etc), ETCOUPLTYPE(etcVRESCALE));
234 if (ir->fepvals->delta_lambda != 0) /* check this? */
236 gmx_fatal(FARGS, "delta_lambda is not zero");
241 snew(re->pres, re->nrepl);
242 if (ir->epct == epctSURFACETENSION)
244 pres = ir->ref_p[ZZ][ZZ];
250 for (i = 0; i < DIM; i++)
252 if (ir->compress[i][i] != 0)
254 pres += ir->ref_p[i][i];
260 re->pres[re->repl] = pres;
261 gmx_sum_sim(re->nrepl, re->pres, ms);
264 /* Make an index for increasing replica order */
265 /* only makes sense if one or the other is varying, not both!
266 if both are varying, we trust the order the person gave. */
267 snew(re->ind, re->nrepl);
268 for (i = 0; i < re->nrepl; i++)
273 if (re->type < ereENDSINGLE)
276 for (i = 0; i < re->nrepl; i++)
278 for (j = i+1; j < re->nrepl; j++)
280 if (re->q[re->type][re->ind[j]] < re->q[re->type][re->ind[i]])
283 re->ind[i] = re->ind[j];
286 else if (re->q[re->type][re->ind[j]] == re->q[re->type][re->ind[i]])
288 gmx_fatal(FARGS, "Two replicas have identical %ss", erename[re->type]);
294 /* keep track of all the swaps, starting with the initial placement. */
295 snew(re->allswaps, re->nrepl);
296 for (i = 0; i < re->nrepl; i++)
298 re->allswaps[i] = re->ind[i];
304 fprintf(fplog, "\nReplica exchange in temperature\n");
305 for (i = 0; i < re->nrepl; i++)
307 fprintf(fplog, " %5.1f", re->q[re->type][re->ind[i]]);
309 fprintf(fplog, "\n");
312 fprintf(fplog, "\nReplica exchange in lambda\n");
313 for (i = 0; i < re->nrepl; i++)
315 fprintf(fplog, " %3d", (int)re->q[re->type][re->ind[i]]);
317 fprintf(fplog, "\n");
320 fprintf(fplog, "\nReplica exchange in temperature and lambda state\n");
321 for (i = 0; i < re->nrepl; i++)
323 fprintf(fplog, " %5.1f", re->q[ereTEMP][re->ind[i]]);
325 fprintf(fplog, "\n");
326 for (i = 0; i < re->nrepl; i++)
328 fprintf(fplog, " %5d", (int)re->q[ereLAMBDA][re->ind[i]]);
330 fprintf(fplog, "\n");
333 gmx_incons("Unknown replica exchange quantity");
337 fprintf(fplog, "\nRepl p");
338 for (i = 0; i < re->nrepl; i++)
340 fprintf(fplog, " %5.2f", re->pres[re->ind[i]]);
343 for (i = 0; i < re->nrepl; i++)
345 if ((i > 0) && (re->pres[re->ind[i]] < re->pres[re->ind[i-1]]))
347 fprintf(fplog, "\nWARNING: The reference pressures decrease with increasing temperatures\n\n");
348 fprintf(stderr, "\nWARNING: The reference pressures decrease with increasing temperatures\n\n");
357 re->seed = (int)gmx_rng_make_seed();
363 gmx_sumi_sim(1, &(re->seed), ms);
367 re->seed = init_seed;
369 fprintf(fplog, "\nReplica exchange interval: %d\n", re->nst);
370 fprintf(fplog, "\nReplica random seed: %d\n", re->seed);
371 re->rng = gmx_rng_init(re->seed);
376 snew(re->prob_sum, re->nrepl);
377 snew(re->nexchange, re->nrepl);
378 snew(re->nmoves, re->nrepl);
379 for (i = 0; i < re->nrepl; i++)
381 snew(re->nmoves[i], re->nrepl);
383 fprintf(fplog, "Replica exchange information below: x=exchange, pr=probability\n");
385 /* generate space for the helper functions so we don't have to snew each time */
387 snew(re->destinations, re->nrepl);
388 snew(re->incycle, re->nrepl);
389 snew(re->tmpswap, re->nrepl);
390 snew(re->cyclic, re->nrepl);
391 snew(re->order, re->nrepl);
392 for (i = 0; i < re->nrepl; i++)
394 snew(re->cyclic[i], re->nrepl);
395 snew(re->order[i], re->nrepl);
397 /* allocate space for the functions storing the data for the replicas */
398 /* not all of these arrays needed in all cases, but they don't take
399 up much space, since the max size is nrepl**2 */
400 snew(re->prob, re->nrepl);
401 snew(re->bEx, re->nrepl);
402 snew(re->beta, re->nrepl);
403 snew(re->Vol, re->nrepl);
404 snew(re->Epot, re->nrepl);
405 snew(re->de, re->nrepl);
406 for (i = 0; i < re->nrepl; i++)
408 snew(re->de[i], re->nrepl);
414 static void exchange_reals(const gmx_multisim_t gmx_unused *ms, int gmx_unused b, real *v, int n)
424 MPI_Sendrecv(v, n*sizeof(real),MPI_BYTE,MSRANK(ms,b),0,
425 buf,n*sizeof(real),MPI_BYTE,MSRANK(ms,b),0,
426 ms->mpi_comm_masters,MPI_STATUS_IGNORE);
431 MPI_Isend(v, n*sizeof(real), MPI_BYTE, MSRANK(ms, b), 0,
432 ms->mpi_comm_masters, &mpi_req);
433 MPI_Recv(buf, n*sizeof(real), MPI_BYTE, MSRANK(ms, b), 0,
434 ms->mpi_comm_masters, MPI_STATUS_IGNORE);
435 MPI_Wait(&mpi_req, MPI_STATUS_IGNORE);
438 for (i = 0; i < n; i++)
447 static void exchange_ints(const gmx_multisim_t gmx_unused *ms, int gmx_unused b, int *v, int n)
457 MPI_Sendrecv(v, n*sizeof(int),MPI_BYTE,MSRANK(ms,b),0,
458 buf,n*sizeof(int),MPI_BYTE,MSRANK(ms,b),0,
459 ms->mpi_comm_masters,MPI_STATUS_IGNORE);
464 MPI_Isend(v, n*sizeof(int), MPI_BYTE, MSRANK(ms, b), 0,
465 ms->mpi_comm_masters, &mpi_req);
466 MPI_Recv(buf, n*sizeof(int), MPI_BYTE, MSRANK(ms, b), 0,
467 ms->mpi_comm_masters, MPI_STATUS_IGNORE);
468 MPI_Wait(&mpi_req, MPI_STATUS_IGNORE);
471 for (i = 0; i < n; i++)
479 static void exchange_doubles(const gmx_multisim_t gmx_unused *ms, int gmx_unused b, double *v, int n)
489 MPI_Sendrecv(v, n*sizeof(double),MPI_BYTE,MSRANK(ms,b),0,
490 buf,n*sizeof(double),MPI_BYTE,MSRANK(ms,b),0,
491 ms->mpi_comm_masters,MPI_STATUS_IGNORE);
496 MPI_Isend(v, n*sizeof(double), MPI_BYTE, MSRANK(ms, b), 0,
497 ms->mpi_comm_masters, &mpi_req);
498 MPI_Recv(buf, n*sizeof(double), MPI_BYTE, MSRANK(ms, b), 0,
499 ms->mpi_comm_masters, MPI_STATUS_IGNORE);
500 MPI_Wait(&mpi_req, MPI_STATUS_IGNORE);
503 for (i = 0; i < n; i++)
511 static void exchange_rvecs(const gmx_multisim_t gmx_unused *ms, int gmx_unused b, rvec *v, int n)
521 MPI_Sendrecv(v[0], n*sizeof(rvec),MPI_BYTE,MSRANK(ms,b),0,
522 buf[0],n*sizeof(rvec),MPI_BYTE,MSRANK(ms,b),0,
523 ms->mpi_comm_masters,MPI_STATUS_IGNORE);
528 MPI_Isend(v[0], n*sizeof(rvec), MPI_BYTE, MSRANK(ms, b), 0,
529 ms->mpi_comm_masters, &mpi_req);
530 MPI_Recv(buf[0], n*sizeof(rvec), MPI_BYTE, MSRANK(ms, b), 0,
531 ms->mpi_comm_masters, MPI_STATUS_IGNORE);
532 MPI_Wait(&mpi_req, MPI_STATUS_IGNORE);
535 for (i = 0; i < n; i++)
537 copy_rvec(buf[i], v[i]);
543 static void exchange_state(const gmx_multisim_t *ms, int b, t_state *state)
545 /* When t_state changes, this code should be updated. */
547 ngtc = state->ngtc * state->nhchainlength;
548 nnhpres = state->nnhpres* state->nhchainlength;
549 exchange_rvecs(ms, b, state->box, DIM);
550 exchange_rvecs(ms, b, state->box_rel, DIM);
551 exchange_rvecs(ms, b, state->boxv, DIM);
552 exchange_reals(ms, b, &(state->veta), 1);
553 exchange_reals(ms, b, &(state->vol0), 1);
554 exchange_rvecs(ms, b, state->svir_prev, DIM);
555 exchange_rvecs(ms, b, state->fvir_prev, DIM);
556 exchange_rvecs(ms, b, state->pres_prev, DIM);
557 exchange_doubles(ms, b, state->nosehoover_xi, ngtc);
558 exchange_doubles(ms, b, state->nosehoover_vxi, ngtc);
559 exchange_doubles(ms, b, state->nhpres_xi, nnhpres);
560 exchange_doubles(ms, b, state->nhpres_vxi, nnhpres);
561 exchange_doubles(ms, b, state->therm_integral, state->ngtc);
562 exchange_rvecs(ms, b, state->x, state->natoms);
563 exchange_rvecs(ms, b, state->v, state->natoms);
564 exchange_rvecs(ms, b, state->sd_X, state->natoms);
567 static void copy_rvecs(rvec *s, rvec *d, int n)
573 for (i = 0; i < n; i++)
575 copy_rvec(s[i], d[i]);
580 static void copy_doubles(const double *s, double *d, int n)
586 for (i = 0; i < n; i++)
593 static void copy_reals(const real *s, real *d, int n)
599 for (i = 0; i < n; i++)
606 static void copy_ints(const int *s, int *d, int n)
612 for (i = 0; i < n; i++)
619 #define scopy_rvecs(v, n) copy_rvecs(state->v, state_local->v, n);
620 #define scopy_doubles(v, n) copy_doubles(state->v, state_local->v, n);
621 #define scopy_reals(v, n) copy_reals(state->v, state_local->v, n);
622 #define scopy_ints(v, n) copy_ints(state->v, state_local->v, n);
624 static void copy_state_nonatomdata(t_state *state, t_state *state_local)
626 /* When t_state changes, this code should be updated. */
628 ngtc = state->ngtc * state->nhchainlength;
629 nnhpres = state->nnhpres* state->nhchainlength;
630 scopy_rvecs(box, DIM);
631 scopy_rvecs(box_rel, DIM);
632 scopy_rvecs(boxv, DIM);
633 state_local->veta = state->veta;
634 state_local->vol0 = state->vol0;
635 scopy_rvecs(svir_prev, DIM);
636 scopy_rvecs(fvir_prev, DIM);
637 scopy_rvecs(pres_prev, DIM);
638 scopy_doubles(nosehoover_xi, ngtc);
639 scopy_doubles(nosehoover_vxi, ngtc);
640 scopy_doubles(nhpres_xi, nnhpres);
641 scopy_doubles(nhpres_vxi, nnhpres);
642 scopy_doubles(therm_integral, state->ngtc);
643 scopy_rvecs(x, state->natoms);
644 scopy_rvecs(v, state->natoms);
645 scopy_rvecs(sd_X, state->natoms);
646 copy_ints(&(state->fep_state), &(state_local->fep_state), 1);
647 scopy_reals(lambda, efptNR);
650 static void scale_velocities(t_state *state, real fac)
656 for (i = 0; i < state->natoms; i++)
658 svmul(fac, state->v[i], state->v[i]);
663 static void print_transition_matrix(FILE *fplog, int n, int **nmoves, int *nattempt)
668 ntot = nattempt[0] + nattempt[1];
669 fprintf(fplog, "\n");
670 fprintf(fplog, "Repl");
671 for (i = 0; i < n; i++)
673 fprintf(fplog, " "); /* put the title closer to the center */
675 fprintf(fplog, "Empirical Transition Matrix\n");
677 fprintf(fplog, "Repl");
678 for (i = 0; i < n; i++)
680 fprintf(fplog, "%8d", (i+1));
682 fprintf(fplog, "\n");
684 for (i = 0; i < n; i++)
686 fprintf(fplog, "Repl");
687 for (j = 0; j < n; j++)
690 if (nmoves[i][j] > 0)
692 Tprint = nmoves[i][j]/(2.0*ntot);
694 fprintf(fplog, "%8.4f", Tprint);
696 fprintf(fplog, "%3d\n", i);
700 static void print_ind(FILE *fplog, const char *leg, int n, int *ind, gmx_bool *bEx)
704 fprintf(fplog, "Repl %2s %2d", leg, ind[0]);
705 for (i = 1; i < n; i++)
707 fprintf(fplog, " %c %2d", (bEx != 0 && bEx[i]) ? 'x' : ' ', ind[i]);
709 fprintf(fplog, "\n");
712 static void print_allswitchind(FILE *fplog, int n, int *pind, int *allswaps, int *tmpswap)
716 for (i = 0; i < n; i++)
718 tmpswap[i] = allswaps[i];
720 for (i = 0; i < n; i++)
722 allswaps[i] = tmpswap[pind[i]];
725 fprintf(fplog, "\nAccepted Exchanges: ");
726 for (i = 0; i < n; i++)
728 fprintf(fplog, "%d ", pind[i]);
730 fprintf(fplog, "\n");
732 /* the "Order After Exchange" is the state label corresponding to the configuration that
733 started in state listed in order, i.e.
738 configuration starting in simulation 3 is now in simulation 0,
739 configuration starting in simulation 0 is now in simulation 1,
740 configuration starting in simulation 1 is now in simulation 2,
741 configuration starting in simulation 2 is now in simulation 3
743 fprintf(fplog, "Order After Exchange: ");
744 for (i = 0; i < n; i++)
746 fprintf(fplog, "%d ", allswaps[i]);
748 fprintf(fplog, "\n\n");
751 static void print_prob(FILE *fplog, const char *leg, int n, real *prob)
756 fprintf(fplog, "Repl %2s ", leg);
757 for (i = 1; i < n; i++)
761 sprintf(buf, "%4.2f", prob[i]);
762 fprintf(fplog, " %3s", buf[0] == '1' ? "1.0" : buf+1);
769 fprintf(fplog, "\n");
772 static void print_count(FILE *fplog, const char *leg, int n, int *count)
776 fprintf(fplog, "Repl %2s ", leg);
777 for (i = 1; i < n; i++)
779 fprintf(fplog, " %4d", count[i]);
781 fprintf(fplog, "\n");
784 static real calc_delta(FILE *fplog, gmx_bool bPrint, struct gmx_repl_ex *re, int a, int b, int ap, int bp)
787 real ediff, dpV, delta = 0;
788 real *Epot = re->Epot;
791 real *beta = re->beta;
793 /* Two cases; we are permuted and not. In all cases, setting ap = a and bp = b will reduce
794 to the non permuted case */
800 * Okabe et. al. Chem. Phys. Lett. 335 (2001) 435-439
802 ediff = Epot[b] - Epot[a];
803 delta = -(beta[bp] - beta[ap])*ediff;
806 /* two cases: when we are permuted, and not. */
808 ediff = E_new - E_old
809 = [H_b(x_a) + H_a(x_b)] - [H_b(x_b) + H_a(x_a)]
810 = [H_b(x_a) - H_a(x_a)] + [H_a(x_b) - H_b(x_b)]
811 = de[b][a] + de[a][b] */
814 ediff = E_new - E_old
815 = [H_bp(x_a) + H_ap(x_b)] - [H_bp(x_b) + H_ap(x_a)]
816 = [H_bp(x_a) - H_ap(x_a)] + [H_ap(x_b) - H_bp(x_b)]
817 = [H_bp(x_a) - H_a(x_a) + H_a(x_a) - H_ap(x_a)] + [H_ap(x_b) - H_b(x_b) + H_b(x_b) - H_bp(x_b)]
818 = [H_bp(x_a) - H_a(x_a)] - [H_ap(x_a) - H_a(x_a)] + [H_ap(x_b) - H_b(x_b)] - H_bp(x_b) - H_b(x_b)]
819 = (de[bp][a] - de[ap][a]) + (de[ap][b] - de[bp][b]) */
820 /* but, in the current code implementation, we flip configurations, not indices . . .
821 So let's examine that.
822 = [H_b(x_ap) - H_a(x_a)] - [H_a(x_ap) - H_a(x_a)] + [H_a(x_bp) - H_b(x_b)] - H_b(x_bp) - H_b(x_b)]
823 = [H_b(x_ap) - H_a(x_ap)] + [H_a(x_bp) - H_b(x_pb)]
824 = (de[b][ap] - de[a][ap]) + (de[a][bp] - de[b][bp]
825 So, if we exchange b<=> bp and a<=> ap, we return to the same result.
826 So the simple solution is to flip the
827 position of perturbed and original indices in the tests.
830 ediff = (de[bp][a] - de[ap][a]) + (de[ap][b] - de[bp][b]);
831 delta = ediff*beta[a]; /* assume all same temperature in this case */
835 /* delta = reduced E_new - reduced E_old
836 = [beta_b H_b(x_a) + beta_a H_a(x_b)] - [beta_b H_b(x_b) + beta_a H_a(x_a)]
837 = [beta_b H_b(x_a) - beta_a H_a(x_a)] + [beta_a H_a(x_b) - beta_b H_b(x_b)]
838 = [beta_b dH_b(x_a) + beta_b H_a(x_a) - beta_a H_a(x_a)] +
839 [beta_a dH_a(x_b) + beta_a H_b(x_b) - beta_b H_b(x_b)]
840 = [beta_b dH_b(x_a) + [beta_a dH_a(x_b) +
841 beta_b (H_a(x_a) - H_b(x_b)]) - beta_a (H_a(x_a) - H_b(x_b))
842 = beta_b dH_b(x_a) + beta_a dH_a(x_b) - (beta_b - beta_a)(H_b(x_b) - H_a(x_a) */
843 /* delta = beta[b]*de[b][a] + beta[a]*de[a][b] - (beta[b] - beta[a])*(Epot[b] - Epot[a]; */
844 /* permuted (big breath!) */
845 /* delta = reduced E_new - reduced E_old
846 = [beta_bp H_bp(x_a) + beta_ap H_ap(x_b)] - [beta_bp H_bp(x_b) + beta_ap H_ap(x_a)]
847 = [beta_bp H_bp(x_a) - beta_ap H_ap(x_a)] + [beta_ap H_ap(x_b) - beta_bp H_bp(x_b)]
848 = [beta_bp H_bp(x_a) - beta_ap H_ap(x_a)] + [beta_ap H_ap(x_b) - beta_bp H_bp(x_b)]
849 - beta_pb H_a(x_a) + beta_ap H_a(x_a) + beta_pb H_a(x_a) - beta_ap H_a(x_a)
850 - beta_ap H_b(x_b) + beta_bp H_b(x_b) + beta_ap H_b(x_b) - beta_bp H_b(x_b)
851 = [(beta_bp H_bp(x_a) - beta_bp H_a(x_a)) - (beta_ap H_ap(x_a) - beta_ap H_a(x_a))] +
852 [(beta_ap H_ap(x_b) - beta_ap H_b(x_b)) - (beta_bp H_bp(x_b) - beta_bp H_b(x_b))]
853 + beta_pb H_a(x_a) - beta_ap H_a(x_a) + beta_ap H_b(x_b) - beta_bp H_b(x_b)
854 = [beta_bp (H_bp(x_a) - H_a(x_a)) - beta_ap (H_ap(x_a) - H_a(x_a))] +
855 [beta_ap (H_ap(x_b) - H_b(x_b)) - beta_bp (H_bp(x_b) - H_b(x_b))]
856 + beta_pb (H_a(x_a) - H_b(x_b)) - beta_ap (H_a(x_a) - H_b(x_b))
857 = ([beta_bp de[bp][a] - beta_ap de[ap][a]) + beta_ap de[ap][b] - beta_bp de[bp][b])
858 + (beta_pb-beta_ap)(H_a(x_a) - H_b(x_b)) */
859 delta = beta[bp]*(de[bp][a] - de[bp][b]) + beta[ap]*(de[ap][b] - de[ap][a]) - (beta[bp]-beta[ap])*(Epot[b]-Epot[a]);
862 gmx_incons("Unknown replica exchange quantity");
866 fprintf(fplog, "Repl %d <-> %d dE_term = %10.3e (kT)\n", a, b, delta);
870 /* revist the calculation for 5.0. Might be some improvements. */
871 dpV = (beta[ap]*re->pres[ap]-beta[bp]*re->pres[bp])*(Vol[b]-Vol[a])/PRESFAC;
874 fprintf(fplog, " dpV = %10.3e d = %10.3e\nb", dpV, delta + dpV);
882 test_for_replica_exchange(FILE *fplog,
883 const gmx_multisim_t *ms,
884 struct gmx_repl_ex *re,
885 gmx_enerdata_t *enerd,
890 int m, i, j, a, b, ap, bp, i0, i1, tmp;
891 real ediff = 0, delta = 0, dpV = 0;
892 gmx_bool bPrint, bMultiEx;
893 gmx_bool *bEx = re->bEx;
894 real *prob = re->prob;
895 int *pind = re->destinations; /* permuted index */
896 gmx_bool bEpot = FALSE;
897 gmx_bool bDLambda = FALSE;
898 gmx_bool bVol = FALSE;
901 bMultiEx = (re->nex > 1); /* multiple exchanges at each state */
902 fprintf(fplog, "Replica exchange at step " "%"GMX_PRId64 " time %g\n", step, time);
906 for (i = 0; i < re->nrepl; i++)
911 re->Vol[re->repl] = vol;
913 if ((re->type == ereTEMP || re->type == ereTL))
915 for (i = 0; i < re->nrepl; i++)
920 re->Epot[re->repl] = enerd->term[F_EPOT];
921 /* temperatures of different states*/
922 for (i = 0; i < re->nrepl; i++)
924 re->beta[i] = 1.0/(re->q[ereTEMP][i]*BOLTZ);
929 for (i = 0; i < re->nrepl; i++)
931 re->beta[i] = 1.0/(re->temp*BOLTZ); /* we have a single temperature */
934 if (re->type == ereLAMBDA || re->type == ereTL)
937 /* lambda differences. */
938 /* de[i][j] is the energy of the jth simulation in the ith Hamiltonian
939 minus the energy of the jth simulation in the jth Hamiltonian */
940 for (i = 0; i < re->nrepl; i++)
942 for (j = 0; j < re->nrepl; j++)
947 for (i = 0; i < re->nrepl; i++)
949 re->de[i][re->repl] = (enerd->enerpart_lambda[(int)re->q[ereLAMBDA][i]+1]-enerd->enerpart_lambda[0]);
953 /* now actually do the communication */
956 gmx_sum_sim(re->nrepl, re->Vol, ms);
960 gmx_sum_sim(re->nrepl, re->Epot, ms);
964 for (i = 0; i < re->nrepl; i++)
966 gmx_sum_sim(re->nrepl, re->de[i], ms);
970 /* make a duplicate set of indices for shuffling */
971 for (i = 0; i < re->nrepl; i++)
973 pind[i] = re->ind[i];
978 /* multiple random switch exchange */
980 for (i = 0; i < re->nex + nself; i++)
984 gmx_rng_cycle_2uniform(step, i*2, re->seed, RND_SEED_REPLEX, rnd);
985 /* randomly select a pair */
986 /* in theory, could reduce this by identifying only which switches had a nonneglibible
987 probability of occurring (log p > -100) and only operate on those switches */
988 /* find out which state it is from, and what label that state currently has. Likely
989 more work that useful. */
990 i0 = (int)(re->nrepl*rnd[0]);
991 i1 = (int)(re->nrepl*rnd[1]);
995 continue; /* self-exchange, back up and do it again */
998 a = re->ind[i0]; /* what are the indices of these states? */
1003 bPrint = FALSE; /* too noisy */
1004 /* calculate the energy difference */
1005 /* if the code changes to flip the STATES, rather than the configurations,
1006 use the commented version of the code */
1007 /* delta = calc_delta(fplog,bPrint,re,a,b,ap,bp); */
1008 delta = calc_delta(fplog, bPrint, re, ap, bp, a, b);
1010 /* we actually only use the first space in the prob and bEx array,
1011 since there are actually many switches between pairs. */
1021 if (delta > PROBABILITYCUTOFF)
1027 prob[0] = exp(-delta);
1029 /* roll a number to determine if accepted */
1030 gmx_rng_cycle_2uniform(step, i*2+1, re->seed, RND_SEED_REPLEX, rnd);
1031 bEx[0] = rnd[0] < prob[0];
1033 re->prob_sum[0] += prob[0];
1037 /* swap the states */
1039 pind[i0] = pind[i1];
1043 re->nattempt[0]++; /* keep track of total permutation trials here */
1044 print_allswitchind(fplog, re->nrepl, pind, re->allswaps, re->tmpswap);
1048 /* standard nearest neighbor replica exchange */
1050 m = (step / re->nst) % 2;
1051 for (i = 1; i < re->nrepl; i++)
1056 bPrint = (re->repl == a || re->repl == b);
1059 delta = calc_delta(fplog, bPrint, re, a, b, a, b);
1070 if (delta > PROBABILITYCUTOFF)
1076 prob[i] = exp(-delta);
1078 /* roll a number to determine if accepted */
1079 gmx_rng_cycle_2uniform(step, i, re->seed, RND_SEED_REPLEX, rnd);
1080 bEx[i] = rnd[0] < prob[i];
1082 re->prob_sum[i] += prob[i];
1086 /* swap these two */
1088 pind[i-1] = pind[i];
1090 re->nexchange[i]++; /* statistics for back compatibility */
1099 /* print some statistics */
1100 print_ind(fplog, "ex", re->nrepl, re->ind, bEx);
1101 print_prob(fplog, "pr", re->nrepl, prob);
1102 fprintf(fplog, "\n");
1106 /* record which moves were made and accepted */
1107 for (i = 0; i < re->nrepl; i++)
1109 re->nmoves[re->ind[i]][pind[i]] += 1;
1110 re->nmoves[pind[i]][re->ind[i]] += 1;
1112 fflush(fplog); /* make sure we can see what the last exchange was */
1115 static void write_debug_x(t_state *state)
1121 for (i = 0; i < state->natoms; i += 10)
1123 fprintf(debug, "dx %5d %10.5f %10.5f %10.5f\n", i, state->x[i][XX], state->x[i][YY], state->x[i][ZZ]);
1129 cyclic_decomposition(const int *destinations,
1138 for (i = 0; i < nrepl; i++)
1142 for (i = 0; i < nrepl; i++) /* one cycle for each replica */
1153 for (j = 0; j < nrepl; j++) /* potentially all cycles are part, but we will break first */
1155 p = destinations[p]; /* start permuting */
1163 break; /* we've reached the original element, the cycle is complete, and we marked the end. */
1167 cyclic[i][c] = p; /* each permutation gives a new member of the cycle */
1173 *nswap = maxlen - 1;
1177 for (i = 0; i < nrepl; i++)
1179 fprintf(debug, "Cycle %d:", i);
1180 for (j = 0; j < nrepl; j++)
1182 if (cyclic[i][j] < 0)
1186 fprintf(debug, "%2d", cyclic[i][j]);
1188 fprintf(debug, "\n");
1195 compute_exchange_order(FILE *fplog,
1203 for (j = 0; j < maxswap; j++)
1205 for (i = 0; i < nrepl; i++)
1207 if (cyclic[i][j+1] >= 0)
1209 order[cyclic[i][j+1]][j] = cyclic[i][j];
1210 order[cyclic[i][j]][j] = cyclic[i][j+1];
1213 for (i = 0; i < nrepl; i++)
1215 if (order[i][j] < 0)
1217 order[i][j] = i; /* if it's not exchanging, it should stay this round*/
1224 fprintf(fplog, "Replica Exchange Order\n");
1225 for (i = 0; i < nrepl; i++)
1227 fprintf(fplog, "Replica %d:", i);
1228 for (j = 0; j < maxswap; j++)
1230 if (order[i][j] < 0)
1234 fprintf(debug, "%2d", order[i][j]);
1236 fprintf(fplog, "\n");
1243 prepare_to_do_exchange(FILE *fplog,
1244 const int *destinations,
1245 const int replica_id,
1251 gmx_bool *bThisReplicaExchanged)
1254 /* Hold the cyclic decomposition of the (multiple) replica
1256 gmx_bool bAnyReplicaExchanged = FALSE;
1257 *bThisReplicaExchanged = FALSE;
1259 for (i = 0; i < nrepl; i++)
1261 if (destinations[i] != i)
1263 /* only mark as exchanged if the index has been shuffled */
1264 bAnyReplicaExchanged = TRUE;
1268 if (bAnyReplicaExchanged)
1270 /* reinitialize the placeholder arrays */
1271 for (i = 0; i < nrepl; i++)
1273 for (j = 0; j < nrepl; j++)
1280 /* Identify the cyclic decomposition of the permutation (very
1281 * fast if neighbor replica exchange). */
1282 cyclic_decomposition(destinations, cyclic, incycle, nrepl, maxswap);
1284 /* Now translate the decomposition into a replica exchange
1285 * order at each step. */
1286 compute_exchange_order(fplog, cyclic, order, nrepl, *maxswap);
1288 /* Did this replica do any exchange at any point? */
1289 for (j = 0; j < *maxswap; j++)
1291 if (replica_id != order[replica_id][j])
1293 *bThisReplicaExchanged = TRUE;
1300 gmx_bool replica_exchange(FILE *fplog, const t_commrec *cr, struct gmx_repl_ex *re,
1301 t_state *state, gmx_enerdata_t *enerd,
1302 t_state *state_local, gmx_int64_t step, real time)
1306 int exchange_partner;
1308 /* Number of rounds of exchanges needed to deal with any multiple
1310 /* Where each replica ends up after the exchange attempt(s). */
1311 /* The order in which multiple exchanges will occur. */
1312 gmx_bool bThisReplicaExchanged = FALSE;
1316 replica_id = re->repl;
1317 test_for_replica_exchange(fplog, cr->ms, re, enerd, det(state_local->box), step, time);
1318 prepare_to_do_exchange(fplog, re->destinations, replica_id, re->nrepl, &maxswap,
1319 re->order, re->cyclic, re->incycle, &bThisReplicaExchanged);
1321 /* Do intra-simulation broadcast so all processors belonging to
1322 * each simulation know whether they need to participate in
1323 * collecting the state. Otherwise, they might as well get on with
1324 * the next thing to do. */
1325 if (DOMAINDECOMP(cr))
1328 MPI_Bcast(&bThisReplicaExchanged, sizeof(gmx_bool), MPI_BYTE, MASTERRANK(cr),
1329 cr->mpi_comm_mygroup);
1333 if (bThisReplicaExchanged)
1335 /* Exchange the states */
1336 /* Collect the global state on the master node */
1337 if (DOMAINDECOMP(cr))
1339 dd_collect_state(cr->dd, state_local, state);
1343 copy_state_nonatomdata(state_local, state);
1348 /* There will be only one swap cycle with standard replica
1349 * exchange, but there may be multiple swap cycles if we
1350 * allow multiple swaps. */
1352 for (j = 0; j < maxswap; j++)
1354 exchange_partner = re->order[replica_id][j];
1356 if (exchange_partner != replica_id)
1358 /* Exchange the global states between the master nodes */
1361 fprintf(debug, "Exchanging %d with %d\n", replica_id, exchange_partner);
1363 exchange_state(cr->ms, exchange_partner, state);
1366 /* For temperature-type replica exchange, we need to scale
1367 * the velocities. */
1368 if (re->type == ereTEMP || re->type == ereTL)
1370 scale_velocities(state, sqrt(re->q[ereTEMP][replica_id]/re->q[ereTEMP][re->destinations[replica_id]]));
1375 /* With domain decomposition the global state is distributed later */
1376 if (!DOMAINDECOMP(cr))
1378 /* Copy the global state to the local state data structure */
1379 copy_state_nonatomdata(state, state_local);
1383 return bThisReplicaExchanged;
1386 void print_replica_exchange_statistics(FILE *fplog, struct gmx_repl_ex *re)
1390 fprintf(fplog, "\nReplica exchange statistics\n");
1394 fprintf(fplog, "Repl %d attempts, %d odd, %d even\n",
1395 re->nattempt[0]+re->nattempt[1], re->nattempt[1], re->nattempt[0]);
1397 fprintf(fplog, "Repl average probabilities:\n");
1398 for (i = 1; i < re->nrepl; i++)
1400 if (re->nattempt[i%2] == 0)
1406 re->prob[i] = re->prob_sum[i]/re->nattempt[i%2];
1409 print_ind(fplog, "", re->nrepl, re->ind, NULL);
1410 print_prob(fplog, "", re->nrepl, re->prob);
1412 fprintf(fplog, "Repl number of exchanges:\n");
1413 print_ind(fplog, "", re->nrepl, re->ind, NULL);
1414 print_count(fplog, "", re->nrepl, re->nexchange);
1416 fprintf(fplog, "Repl average number of exchanges:\n");
1417 for (i = 1; i < re->nrepl; i++)
1419 if (re->nattempt[i%2] == 0)
1425 re->prob[i] = ((real)re->nexchange[i])/re->nattempt[i%2];
1428 print_ind(fplog, "", re->nrepl, re->ind, NULL);
1429 print_prob(fplog, "", re->nrepl, re->prob);
1431 fprintf(fplog, "\n");
1433 /* print the transition matrix */
1434 print_transition_matrix(fplog, re->nrepl, re->nmoves, re->nattempt);