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46 #include "gromacs/legacyheaders/network.h"
47 #include "gromacs/random/random.h"
48 #include "gromacs/utility/smalloc.h"
49 #include "gromacs/math/units.h"
50 #include "gromacs/legacyheaders/copyrite.h"
51 #include "gromacs/math/vec.h"
52 #include "gromacs/legacyheaders/names.h"
53 #include "gromacs/legacyheaders/domdec.h"
54 #include "gromacs/legacyheaders/main.h"
55 #include "gromacs/random/random.h"
57 #define PROBABILITYCUTOFF 100
58 /* we don't bother evaluating if events are more rare than exp(-100) = 3.7x10^-44 */
61 ereTEMP, ereLAMBDA, ereENDSINGLE, ereTL, ereNR
63 const char *erename[ereNR] = { "temperature", "lambda", "end_single_marker", "temperature and lambda"};
64 /* end_single_marker merely notes the end of single variable replica exchange. All types higher than
65 it are multiple replica exchange methods */
66 /* Eventually, should add 'pressure', 'temperature and pressure', 'lambda_and_pressure', 'temperature_lambda_pressure'?;
67 Let's wait until we feel better about the pressure control methods giving exact ensembles. Right now, we assume constant pressure */
69 typedef struct gmx_repl_ex
89 /* these are helper arrays for replica exchange; allocated here so they
90 don't have to be allocated each time */
98 /* helper arrays to hold the quantities that are exchanged */
107 static gmx_bool repl_quantity(const gmx_multisim_t *ms,
108 struct gmx_repl_ex *re, int ere, real q)
114 snew(qall, ms->nsim);
116 gmx_sum_sim(ms->nsim, qall, ms);
119 for (s = 1; s < ms->nsim; s++)
121 if (qall[s] != qall[0])
129 /* Set the replica exchange type and quantities */
132 snew(re->q[ere], re->nrepl);
133 for (s = 0; s < ms->nsim; s++)
135 re->q[ere][s] = qall[s];
142 gmx_repl_ex_t init_replica_exchange(FILE *fplog,
143 const gmx_multisim_t *ms,
144 const t_state *state,
145 const t_inputrec *ir,
146 int nst, int nex, int init_seed)
150 struct gmx_repl_ex *re;
152 gmx_bool bLambda = FALSE;
154 fprintf(fplog, "\nInitializing Replica Exchange\n");
156 if (ms == NULL || ms->nsim == 1)
158 gmx_fatal(FARGS, "Nothing to exchange with only one replica, maybe you forgot to set the -multi option of mdrun?");
160 if (!EI_DYNAMICS(ir->eI))
162 gmx_fatal(FARGS, "Replica exchange is only supported by dynamical simulations");
163 /* Note that PAR(cr) is defined by cr->nnodes > 1, which is
164 * distinct from MULTISIM(cr). A multi-simulation only runs
165 * with real MPI parallelism, but this does not imply PAR(cr)
168 * Since we are using a dynamical integrator, the only
169 * decomposition is DD, so PAR(cr) and DOMAINDECOMP(cr) are
170 * synonymous. The only way for cr->nnodes > 1 to be true is
171 * if we are using DD. */
177 re->nrepl = ms->nsim;
178 snew(re->q, ereENDSINGLE);
180 fprintf(fplog, "Repl There are %d replicas:\n", re->nrepl);
182 check_multi_int(fplog, ms, state->natoms, "the number of atoms", FALSE);
183 check_multi_int(fplog, ms, ir->eI, "the integrator", FALSE);
184 check_multi_int64(fplog, ms, ir->init_step+ir->nsteps, "init_step+nsteps", FALSE);
185 check_multi_int64(fplog, ms, (ir->init_step+nst-1)/nst,
186 "first exchange step: init_step/-replex", FALSE);
187 check_multi_int(fplog, ms, ir->etc, "the temperature coupling", FALSE);
188 check_multi_int(fplog, ms, ir->opts.ngtc,
189 "the number of temperature coupling groups", FALSE);
190 check_multi_int(fplog, ms, ir->epc, "the pressure coupling", FALSE);
191 check_multi_int(fplog, ms, ir->efep, "free energy", FALSE);
192 check_multi_int(fplog, ms, ir->fepvals->n_lambda, "number of lambda states", FALSE);
194 re->temp = ir->opts.ref_t[0];
195 for (i = 1; (i < ir->opts.ngtc); i++)
197 if (ir->opts.ref_t[i] != re->temp)
199 fprintf(fplog, "\nWARNING: The temperatures of the different temperature coupling groups are not identical\n\n");
200 fprintf(stderr, "\nWARNING: The temperatures of the different temperature coupling groups are not identical\n\n");
205 bTemp = repl_quantity(ms, re, ereTEMP, re->temp);
206 if (ir->efep != efepNO)
208 bLambda = repl_quantity(ms, re, ereLAMBDA, (real)ir->fepvals->init_fep_state);
210 if (re->type == -1) /* nothing was assigned */
212 gmx_fatal(FARGS, "The properties of the %d systems are all the same, there is nothing to exchange", re->nrepl);
214 if (bLambda && bTemp)
221 please_cite(fplog, "Sugita1999a");
222 if (ir->epc != epcNO)
225 fprintf(fplog, "Repl Using Constant Pressure REMD.\n");
226 please_cite(fplog, "Okabe2001a");
228 if (ir->etc == etcBERENDSEN)
230 gmx_fatal(FARGS, "REMD with the %s thermostat does not produce correct potential energy distributions, consider using the %s thermostat instead",
231 ETCOUPLTYPE(ir->etc), ETCOUPLTYPE(etcVRESCALE));
236 if (ir->fepvals->delta_lambda != 0) /* check this? */
238 gmx_fatal(FARGS, "delta_lambda is not zero");
243 snew(re->pres, re->nrepl);
244 if (ir->epct == epctSURFACETENSION)
246 pres = ir->ref_p[ZZ][ZZ];
252 for (i = 0; i < DIM; i++)
254 if (ir->compress[i][i] != 0)
256 pres += ir->ref_p[i][i];
262 re->pres[re->repl] = pres;
263 gmx_sum_sim(re->nrepl, re->pres, ms);
266 /* Make an index for increasing replica order */
267 /* only makes sense if one or the other is varying, not both!
268 if both are varying, we trust the order the person gave. */
269 snew(re->ind, re->nrepl);
270 for (i = 0; i < re->nrepl; i++)
275 if (re->type < ereENDSINGLE)
278 for (i = 0; i < re->nrepl; i++)
280 for (j = i+1; j < re->nrepl; j++)
282 if (re->q[re->type][re->ind[j]] < re->q[re->type][re->ind[i]])
284 /* Unordered replicas are supposed to work, but there
285 * is still an issues somewhere.
286 * Note that at this point still re->ind[i]=i.
288 gmx_fatal(FARGS, "Replicas with indices %d < %d have %ss %g > %g, please order your replicas on increasing %s",
291 re->q[re->type][i], re->q[re->type][j],
295 re->ind[i] = re->ind[j];
298 else if (re->q[re->type][re->ind[j]] == re->q[re->type][re->ind[i]])
300 gmx_fatal(FARGS, "Two replicas have identical %ss", erename[re->type]);
306 /* keep track of all the swaps, starting with the initial placement. */
307 snew(re->allswaps, re->nrepl);
308 for (i = 0; i < re->nrepl; i++)
310 re->allswaps[i] = re->ind[i];
316 fprintf(fplog, "\nReplica exchange in temperature\n");
317 for (i = 0; i < re->nrepl; i++)
319 fprintf(fplog, " %5.1f", re->q[re->type][re->ind[i]]);
321 fprintf(fplog, "\n");
324 fprintf(fplog, "\nReplica exchange in lambda\n");
325 for (i = 0; i < re->nrepl; i++)
327 fprintf(fplog, " %3d", (int)re->q[re->type][re->ind[i]]);
329 fprintf(fplog, "\n");
332 fprintf(fplog, "\nReplica exchange in temperature and lambda state\n");
333 for (i = 0; i < re->nrepl; i++)
335 fprintf(fplog, " %5.1f", re->q[ereTEMP][re->ind[i]]);
337 fprintf(fplog, "\n");
338 for (i = 0; i < re->nrepl; i++)
340 fprintf(fplog, " %5d", (int)re->q[ereLAMBDA][re->ind[i]]);
342 fprintf(fplog, "\n");
345 gmx_incons("Unknown replica exchange quantity");
349 fprintf(fplog, "\nRepl p");
350 for (i = 0; i < re->nrepl; i++)
352 fprintf(fplog, " %5.2f", re->pres[re->ind[i]]);
355 for (i = 0; i < re->nrepl; i++)
357 if ((i > 0) && (re->pres[re->ind[i]] < re->pres[re->ind[i-1]]))
359 fprintf(fplog, "\nWARNING: The reference pressures decrease with increasing temperatures\n\n");
360 fprintf(stderr, "\nWARNING: The reference pressures decrease with increasing temperatures\n\n");
369 re->seed = (int)gmx_rng_make_seed();
375 gmx_sumi_sim(1, &(re->seed), ms);
379 re->seed = init_seed;
381 fprintf(fplog, "\nReplica exchange interval: %d\n", re->nst);
382 fprintf(fplog, "\nReplica random seed: %d\n", re->seed);
383 re->rng = gmx_rng_init(re->seed);
388 snew(re->prob_sum, re->nrepl);
389 snew(re->nexchange, re->nrepl);
390 snew(re->nmoves, re->nrepl);
391 for (i = 0; i < re->nrepl; i++)
393 snew(re->nmoves[i], re->nrepl);
395 fprintf(fplog, "Replica exchange information below: x=exchange, pr=probability\n");
397 /* generate space for the helper functions so we don't have to snew each time */
399 snew(re->destinations, re->nrepl);
400 snew(re->incycle, re->nrepl);
401 snew(re->tmpswap, re->nrepl);
402 snew(re->cyclic, re->nrepl);
403 snew(re->order, re->nrepl);
404 for (i = 0; i < re->nrepl; i++)
406 snew(re->cyclic[i], re->nrepl);
407 snew(re->order[i], re->nrepl);
409 /* allocate space for the functions storing the data for the replicas */
410 /* not all of these arrays needed in all cases, but they don't take
411 up much space, since the max size is nrepl**2 */
412 snew(re->prob, re->nrepl);
413 snew(re->bEx, re->nrepl);
414 snew(re->beta, re->nrepl);
415 snew(re->Vol, re->nrepl);
416 snew(re->Epot, re->nrepl);
417 snew(re->de, re->nrepl);
418 for (i = 0; i < re->nrepl; i++)
420 snew(re->de[i], re->nrepl);
426 static void exchange_reals(const gmx_multisim_t gmx_unused *ms, int gmx_unused b, real *v, int n)
436 MPI_Sendrecv(v, n*sizeof(real),MPI_BYTE,MSRANK(ms,b),0,
437 buf,n*sizeof(real),MPI_BYTE,MSRANK(ms,b),0,
438 ms->mpi_comm_masters,MPI_STATUS_IGNORE);
443 MPI_Isend(v, n*sizeof(real), MPI_BYTE, MSRANK(ms, b), 0,
444 ms->mpi_comm_masters, &mpi_req);
445 MPI_Recv(buf, n*sizeof(real), MPI_BYTE, MSRANK(ms, b), 0,
446 ms->mpi_comm_masters, MPI_STATUS_IGNORE);
447 MPI_Wait(&mpi_req, MPI_STATUS_IGNORE);
450 for (i = 0; i < n; i++)
459 static void exchange_ints(const gmx_multisim_t gmx_unused *ms, int gmx_unused b, int *v, int n)
469 MPI_Sendrecv(v, n*sizeof(int),MPI_BYTE,MSRANK(ms,b),0,
470 buf,n*sizeof(int),MPI_BYTE,MSRANK(ms,b),0,
471 ms->mpi_comm_masters,MPI_STATUS_IGNORE);
476 MPI_Isend(v, n*sizeof(int), MPI_BYTE, MSRANK(ms, b), 0,
477 ms->mpi_comm_masters, &mpi_req);
478 MPI_Recv(buf, n*sizeof(int), MPI_BYTE, MSRANK(ms, b), 0,
479 ms->mpi_comm_masters, MPI_STATUS_IGNORE);
480 MPI_Wait(&mpi_req, MPI_STATUS_IGNORE);
483 for (i = 0; i < n; i++)
491 static void exchange_doubles(const gmx_multisim_t gmx_unused *ms, int gmx_unused b, double *v, int n)
501 MPI_Sendrecv(v, n*sizeof(double),MPI_BYTE,MSRANK(ms,b),0,
502 buf,n*sizeof(double),MPI_BYTE,MSRANK(ms,b),0,
503 ms->mpi_comm_masters,MPI_STATUS_IGNORE);
508 MPI_Isend(v, n*sizeof(double), MPI_BYTE, MSRANK(ms, b), 0,
509 ms->mpi_comm_masters, &mpi_req);
510 MPI_Recv(buf, n*sizeof(double), MPI_BYTE, MSRANK(ms, b), 0,
511 ms->mpi_comm_masters, MPI_STATUS_IGNORE);
512 MPI_Wait(&mpi_req, MPI_STATUS_IGNORE);
515 for (i = 0; i < n; i++)
523 static void exchange_rvecs(const gmx_multisim_t gmx_unused *ms, int gmx_unused b, rvec *v, int n)
533 MPI_Sendrecv(v[0], n*sizeof(rvec),MPI_BYTE,MSRANK(ms,b),0,
534 buf[0],n*sizeof(rvec),MPI_BYTE,MSRANK(ms,b),0,
535 ms->mpi_comm_masters,MPI_STATUS_IGNORE);
540 MPI_Isend(v[0], n*sizeof(rvec), MPI_BYTE, MSRANK(ms, b), 0,
541 ms->mpi_comm_masters, &mpi_req);
542 MPI_Recv(buf[0], n*sizeof(rvec), MPI_BYTE, MSRANK(ms, b), 0,
543 ms->mpi_comm_masters, MPI_STATUS_IGNORE);
544 MPI_Wait(&mpi_req, MPI_STATUS_IGNORE);
547 for (i = 0; i < n; i++)
549 copy_rvec(buf[i], v[i]);
555 static void exchange_state(const gmx_multisim_t *ms, int b, t_state *state)
557 /* When t_state changes, this code should be updated. */
559 ngtc = state->ngtc * state->nhchainlength;
560 nnhpres = state->nnhpres* state->nhchainlength;
561 exchange_rvecs(ms, b, state->box, DIM);
562 exchange_rvecs(ms, b, state->box_rel, DIM);
563 exchange_rvecs(ms, b, state->boxv, DIM);
564 exchange_reals(ms, b, &(state->veta), 1);
565 exchange_reals(ms, b, &(state->vol0), 1);
566 exchange_rvecs(ms, b, state->svir_prev, DIM);
567 exchange_rvecs(ms, b, state->fvir_prev, DIM);
568 exchange_rvecs(ms, b, state->pres_prev, DIM);
569 exchange_doubles(ms, b, state->nosehoover_xi, ngtc);
570 exchange_doubles(ms, b, state->nosehoover_vxi, ngtc);
571 exchange_doubles(ms, b, state->nhpres_xi, nnhpres);
572 exchange_doubles(ms, b, state->nhpres_vxi, nnhpres);
573 exchange_doubles(ms, b, state->therm_integral, state->ngtc);
574 exchange_rvecs(ms, b, state->x, state->natoms);
575 exchange_rvecs(ms, b, state->v, state->natoms);
576 exchange_rvecs(ms, b, state->sd_X, state->natoms);
579 static void copy_rvecs(rvec *s, rvec *d, int n)
585 for (i = 0; i < n; i++)
587 copy_rvec(s[i], d[i]);
592 static void copy_doubles(const double *s, double *d, int n)
598 for (i = 0; i < n; i++)
605 static void copy_reals(const real *s, real *d, int n)
611 for (i = 0; i < n; i++)
618 static void copy_ints(const int *s, int *d, int n)
624 for (i = 0; i < n; i++)
631 #define scopy_rvecs(v, n) copy_rvecs(state->v, state_local->v, n);
632 #define scopy_doubles(v, n) copy_doubles(state->v, state_local->v, n);
633 #define scopy_reals(v, n) copy_reals(state->v, state_local->v, n);
634 #define scopy_ints(v, n) copy_ints(state->v, state_local->v, n);
636 static void copy_state_nonatomdata(t_state *state, t_state *state_local)
638 /* When t_state changes, this code should be updated. */
640 ngtc = state->ngtc * state->nhchainlength;
641 nnhpres = state->nnhpres* state->nhchainlength;
642 scopy_rvecs(box, DIM);
643 scopy_rvecs(box_rel, DIM);
644 scopy_rvecs(boxv, DIM);
645 state_local->veta = state->veta;
646 state_local->vol0 = state->vol0;
647 scopy_rvecs(svir_prev, DIM);
648 scopy_rvecs(fvir_prev, DIM);
649 scopy_rvecs(pres_prev, DIM);
650 scopy_doubles(nosehoover_xi, ngtc);
651 scopy_doubles(nosehoover_vxi, ngtc);
652 scopy_doubles(nhpres_xi, nnhpres);
653 scopy_doubles(nhpres_vxi, nnhpres);
654 scopy_doubles(therm_integral, state->ngtc);
655 scopy_rvecs(x, state->natoms);
656 scopy_rvecs(v, state->natoms);
657 scopy_rvecs(sd_X, state->natoms);
658 copy_ints(&(state->fep_state), &(state_local->fep_state), 1);
659 scopy_reals(lambda, efptNR);
662 static void scale_velocities(t_state *state, real fac)
668 for (i = 0; i < state->natoms; i++)
670 svmul(fac, state->v[i], state->v[i]);
675 static void print_transition_matrix(FILE *fplog, int n, int **nmoves, int *nattempt)
680 ntot = nattempt[0] + nattempt[1];
681 fprintf(fplog, "\n");
682 fprintf(fplog, "Repl");
683 for (i = 0; i < n; i++)
685 fprintf(fplog, " "); /* put the title closer to the center */
687 fprintf(fplog, "Empirical Transition Matrix\n");
689 fprintf(fplog, "Repl");
690 for (i = 0; i < n; i++)
692 fprintf(fplog, "%8d", (i+1));
694 fprintf(fplog, "\n");
696 for (i = 0; i < n; i++)
698 fprintf(fplog, "Repl");
699 for (j = 0; j < n; j++)
702 if (nmoves[i][j] > 0)
704 Tprint = nmoves[i][j]/(2.0*ntot);
706 fprintf(fplog, "%8.4f", Tprint);
708 fprintf(fplog, "%3d\n", i);
712 static void print_ind(FILE *fplog, const char *leg, int n, int *ind, gmx_bool *bEx)
716 fprintf(fplog, "Repl %2s %2d", leg, ind[0]);
717 for (i = 1; i < n; i++)
719 fprintf(fplog, " %c %2d", (bEx != 0 && bEx[i]) ? 'x' : ' ', ind[i]);
721 fprintf(fplog, "\n");
724 static void print_allswitchind(FILE *fplog, int n, int *pind, int *allswaps, int *tmpswap)
728 for (i = 0; i < n; i++)
730 tmpswap[i] = allswaps[i];
732 for (i = 0; i < n; i++)
734 allswaps[i] = tmpswap[pind[i]];
737 fprintf(fplog, "\nAccepted Exchanges: ");
738 for (i = 0; i < n; i++)
740 fprintf(fplog, "%d ", pind[i]);
742 fprintf(fplog, "\n");
744 /* the "Order After Exchange" is the state label corresponding to the configuration that
745 started in state listed in order, i.e.
750 configuration starting in simulation 3 is now in simulation 0,
751 configuration starting in simulation 0 is now in simulation 1,
752 configuration starting in simulation 1 is now in simulation 2,
753 configuration starting in simulation 2 is now in simulation 3
755 fprintf(fplog, "Order After Exchange: ");
756 for (i = 0; i < n; i++)
758 fprintf(fplog, "%d ", allswaps[i]);
760 fprintf(fplog, "\n\n");
763 static void print_prob(FILE *fplog, const char *leg, int n, real *prob)
768 fprintf(fplog, "Repl %2s ", leg);
769 for (i = 1; i < n; i++)
773 sprintf(buf, "%4.2f", prob[i]);
774 fprintf(fplog, " %3s", buf[0] == '1' ? "1.0" : buf+1);
781 fprintf(fplog, "\n");
784 static void print_count(FILE *fplog, const char *leg, int n, int *count)
788 fprintf(fplog, "Repl %2s ", leg);
789 for (i = 1; i < n; i++)
791 fprintf(fplog, " %4d", count[i]);
793 fprintf(fplog, "\n");
796 static real calc_delta(FILE *fplog, gmx_bool bPrint, struct gmx_repl_ex *re, int a, int b, int ap, int bp)
799 real ediff, dpV, delta = 0;
800 real *Epot = re->Epot;
803 real *beta = re->beta;
805 /* Two cases; we are permuted and not. In all cases, setting ap = a and bp = b will reduce
806 to the non permuted case */
812 * Okabe et. al. Chem. Phys. Lett. 335 (2001) 435-439
814 ediff = Epot[b] - Epot[a];
815 delta = -(beta[bp] - beta[ap])*ediff;
818 /* two cases: when we are permuted, and not. */
820 ediff = E_new - E_old
821 = [H_b(x_a) + H_a(x_b)] - [H_b(x_b) + H_a(x_a)]
822 = [H_b(x_a) - H_a(x_a)] + [H_a(x_b) - H_b(x_b)]
823 = de[b][a] + de[a][b] */
826 ediff = E_new - E_old
827 = [H_bp(x_a) + H_ap(x_b)] - [H_bp(x_b) + H_ap(x_a)]
828 = [H_bp(x_a) - H_ap(x_a)] + [H_ap(x_b) - H_bp(x_b)]
829 = [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)]
830 = [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)]
831 = (de[bp][a] - de[ap][a]) + (de[ap][b] - de[bp][b]) */
832 /* but, in the current code implementation, we flip configurations, not indices . . .
833 So let's examine that.
834 = [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)]
835 = [H_b(x_ap) - H_a(x_ap)] + [H_a(x_bp) - H_b(x_pb)]
836 = (de[b][ap] - de[a][ap]) + (de[a][bp] - de[b][bp]
837 So, if we exchange b<=> bp and a<=> ap, we return to the same result.
838 So the simple solution is to flip the
839 position of perturbed and original indices in the tests.
842 ediff = (de[bp][a] - de[ap][a]) + (de[ap][b] - de[bp][b]);
843 delta = ediff*beta[a]; /* assume all same temperature in this case */
847 /* delta = reduced E_new - reduced E_old
848 = [beta_b H_b(x_a) + beta_a H_a(x_b)] - [beta_b H_b(x_b) + beta_a H_a(x_a)]
849 = [beta_b H_b(x_a) - beta_a H_a(x_a)] + [beta_a H_a(x_b) - beta_b H_b(x_b)]
850 = [beta_b dH_b(x_a) + beta_b H_a(x_a) - beta_a H_a(x_a)] +
851 [beta_a dH_a(x_b) + beta_a H_b(x_b) - beta_b H_b(x_b)]
852 = [beta_b dH_b(x_a) + [beta_a dH_a(x_b) +
853 beta_b (H_a(x_a) - H_b(x_b)]) - beta_a (H_a(x_a) - H_b(x_b))
854 = beta_b dH_b(x_a) + beta_a dH_a(x_b) - (beta_b - beta_a)(H_b(x_b) - H_a(x_a) */
855 /* delta = beta[b]*de[b][a] + beta[a]*de[a][b] - (beta[b] - beta[a])*(Epot[b] - Epot[a]; */
856 /* permuted (big breath!) */
857 /* delta = reduced E_new - reduced E_old
858 = [beta_bp H_bp(x_a) + beta_ap H_ap(x_b)] - [beta_bp H_bp(x_b) + beta_ap H_ap(x_a)]
859 = [beta_bp H_bp(x_a) - beta_ap H_ap(x_a)] + [beta_ap H_ap(x_b) - beta_bp H_bp(x_b)]
860 = [beta_bp H_bp(x_a) - beta_ap H_ap(x_a)] + [beta_ap H_ap(x_b) - beta_bp H_bp(x_b)]
861 - beta_pb H_a(x_a) + beta_ap H_a(x_a) + beta_pb H_a(x_a) - beta_ap H_a(x_a)
862 - beta_ap H_b(x_b) + beta_bp H_b(x_b) + beta_ap H_b(x_b) - beta_bp H_b(x_b)
863 = [(beta_bp H_bp(x_a) - beta_bp H_a(x_a)) - (beta_ap H_ap(x_a) - beta_ap H_a(x_a))] +
864 [(beta_ap H_ap(x_b) - beta_ap H_b(x_b)) - (beta_bp H_bp(x_b) - beta_bp H_b(x_b))]
865 + beta_pb H_a(x_a) - beta_ap H_a(x_a) + beta_ap H_b(x_b) - beta_bp H_b(x_b)
866 = [beta_bp (H_bp(x_a) - H_a(x_a)) - beta_ap (H_ap(x_a) - H_a(x_a))] +
867 [beta_ap (H_ap(x_b) - H_b(x_b)) - beta_bp (H_bp(x_b) - H_b(x_b))]
868 + beta_pb (H_a(x_a) - H_b(x_b)) - beta_ap (H_a(x_a) - H_b(x_b))
869 = ([beta_bp de[bp][a] - beta_ap de[ap][a]) + beta_ap de[ap][b] - beta_bp de[bp][b])
870 + (beta_pb-beta_ap)(H_a(x_a) - H_b(x_b)) */
871 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]);
874 gmx_incons("Unknown replica exchange quantity");
878 fprintf(fplog, "Repl %d <-> %d dE_term = %10.3e (kT)\n", a, b, delta);
882 /* revist the calculation for 5.0. Might be some improvements. */
883 dpV = (beta[ap]*re->pres[ap]-beta[bp]*re->pres[bp])*(Vol[b]-Vol[a])/PRESFAC;
886 fprintf(fplog, " dpV = %10.3e d = %10.3e\n", dpV, delta + dpV);
894 test_for_replica_exchange(FILE *fplog,
895 const gmx_multisim_t *ms,
896 struct gmx_repl_ex *re,
897 gmx_enerdata_t *enerd,
902 int m, i, j, a, b, ap, bp, i0, i1, tmp;
904 gmx_bool bPrint, bMultiEx;
905 gmx_bool *bEx = re->bEx;
906 real *prob = re->prob;
907 int *pind = re->destinations; /* permuted index */
908 gmx_bool bEpot = FALSE;
909 gmx_bool bDLambda = FALSE;
910 gmx_bool bVol = FALSE;
912 bMultiEx = (re->nex > 1); /* multiple exchanges at each state */
913 fprintf(fplog, "Replica exchange at step %" GMX_PRId64 " time %.5f\n", step, time);
917 for (i = 0; i < re->nrepl; i++)
922 re->Vol[re->repl] = vol;
924 if ((re->type == ereTEMP || re->type == ereTL))
926 for (i = 0; i < re->nrepl; i++)
931 re->Epot[re->repl] = enerd->term[F_EPOT];
932 /* temperatures of different states*/
933 for (i = 0; i < re->nrepl; i++)
935 re->beta[i] = 1.0/(re->q[ereTEMP][i]*BOLTZ);
940 for (i = 0; i < re->nrepl; i++)
942 re->beta[i] = 1.0/(re->temp*BOLTZ); /* we have a single temperature */
945 if (re->type == ereLAMBDA || re->type == ereTL)
948 /* lambda differences. */
949 /* de[i][j] is the energy of the jth simulation in the ith Hamiltonian
950 minus the energy of the jth simulation in the jth Hamiltonian */
951 for (i = 0; i < re->nrepl; i++)
953 for (j = 0; j < re->nrepl; j++)
958 for (i = 0; i < re->nrepl; i++)
960 re->de[i][re->repl] = (enerd->enerpart_lambda[(int)re->q[ereLAMBDA][i]+1]-enerd->enerpart_lambda[0]);
964 /* now actually do the communication */
967 gmx_sum_sim(re->nrepl, re->Vol, ms);
971 gmx_sum_sim(re->nrepl, re->Epot, ms);
975 for (i = 0; i < re->nrepl; i++)
977 gmx_sum_sim(re->nrepl, re->de[i], ms);
981 /* make a duplicate set of indices for shuffling */
982 for (i = 0; i < re->nrepl; i++)
984 pind[i] = re->ind[i];
989 /* multiple random switch exchange */
991 for (i = 0; i < re->nex + nself; i++)
995 gmx_rng_cycle_2uniform(step, i*2, re->seed, RND_SEED_REPLEX, rnd);
996 /* randomly select a pair */
997 /* in theory, could reduce this by identifying only which switches had a nonneglibible
998 probability of occurring (log p > -100) and only operate on those switches */
999 /* find out which state it is from, and what label that state currently has. Likely
1000 more work that useful. */
1001 i0 = (int)(re->nrepl*rnd[0]);
1002 i1 = (int)(re->nrepl*rnd[1]);
1006 continue; /* self-exchange, back up and do it again */
1009 a = re->ind[i0]; /* what are the indices of these states? */
1014 bPrint = FALSE; /* too noisy */
1015 /* calculate the energy difference */
1016 /* if the code changes to flip the STATES, rather than the configurations,
1017 use the commented version of the code */
1018 /* delta = calc_delta(fplog,bPrint,re,a,b,ap,bp); */
1019 delta = calc_delta(fplog, bPrint, re, ap, bp, a, b);
1021 /* we actually only use the first space in the prob and bEx array,
1022 since there are actually many switches between pairs. */
1032 if (delta > PROBABILITYCUTOFF)
1038 prob[0] = exp(-delta);
1040 /* roll a number to determine if accepted */
1041 gmx_rng_cycle_2uniform(step, i*2+1, re->seed, RND_SEED_REPLEX, rnd);
1042 bEx[0] = rnd[0] < prob[0];
1044 re->prob_sum[0] += prob[0];
1048 /* swap the states */
1050 pind[i0] = pind[i1];
1054 re->nattempt[0]++; /* keep track of total permutation trials here */
1055 print_allswitchind(fplog, re->nrepl, pind, re->allswaps, re->tmpswap);
1059 /* standard nearest neighbor replica exchange */
1061 m = (step / re->nst) % 2;
1062 for (i = 1; i < re->nrepl; i++)
1067 bPrint = (re->repl == a || re->repl == b);
1070 delta = calc_delta(fplog, bPrint, re, a, b, a, b);
1081 if (delta > PROBABILITYCUTOFF)
1087 prob[i] = exp(-delta);
1089 /* roll a number to determine if accepted */
1090 gmx_rng_cycle_2uniform(step, i, re->seed, RND_SEED_REPLEX, rnd);
1091 bEx[i] = rnd[0] < prob[i];
1093 re->prob_sum[i] += prob[i];
1097 /* swap these two */
1099 pind[i-1] = pind[i];
1101 re->nexchange[i]++; /* statistics for back compatibility */
1110 /* print some statistics */
1111 print_ind(fplog, "ex", re->nrepl, re->ind, bEx);
1112 print_prob(fplog, "pr", re->nrepl, prob);
1113 fprintf(fplog, "\n");
1117 /* record which moves were made and accepted */
1118 for (i = 0; i < re->nrepl; i++)
1120 re->nmoves[re->ind[i]][pind[i]] += 1;
1121 re->nmoves[pind[i]][re->ind[i]] += 1;
1123 fflush(fplog); /* make sure we can see what the last exchange was */
1126 static void write_debug_x(t_state *state)
1132 for (i = 0; i < state->natoms; i += 10)
1134 fprintf(debug, "dx %5d %10.5f %10.5f %10.5f\n", i, state->x[i][XX], state->x[i][YY], state->x[i][ZZ]);
1140 cyclic_decomposition(const int *destinations,
1149 for (i = 0; i < nrepl; i++)
1153 for (i = 0; i < nrepl; i++) /* one cycle for each replica */
1164 for (j = 0; j < nrepl; j++) /* potentially all cycles are part, but we will break first */
1166 p = destinations[p]; /* start permuting */
1174 break; /* we've reached the original element, the cycle is complete, and we marked the end. */
1178 cyclic[i][c] = p; /* each permutation gives a new member of the cycle */
1184 *nswap = maxlen - 1;
1188 for (i = 0; i < nrepl; i++)
1190 fprintf(debug, "Cycle %d:", i);
1191 for (j = 0; j < nrepl; j++)
1193 if (cyclic[i][j] < 0)
1197 fprintf(debug, "%2d", cyclic[i][j]);
1199 fprintf(debug, "\n");
1206 compute_exchange_order(FILE *fplog,
1214 for (j = 0; j < maxswap; j++)
1216 for (i = 0; i < nrepl; i++)
1218 if (cyclic[i][j+1] >= 0)
1220 order[cyclic[i][j+1]][j] = cyclic[i][j];
1221 order[cyclic[i][j]][j] = cyclic[i][j+1];
1224 for (i = 0; i < nrepl; i++)
1226 if (order[i][j] < 0)
1228 order[i][j] = i; /* if it's not exchanging, it should stay this round*/
1235 fprintf(fplog, "Replica Exchange Order\n");
1236 for (i = 0; i < nrepl; i++)
1238 fprintf(fplog, "Replica %d:", i);
1239 for (j = 0; j < maxswap; j++)
1241 if (order[i][j] < 0)
1245 fprintf(debug, "%2d", order[i][j]);
1247 fprintf(fplog, "\n");
1254 prepare_to_do_exchange(FILE *fplog,
1255 struct gmx_repl_ex *re,
1256 const int replica_id,
1258 gmx_bool *bThisReplicaExchanged)
1261 /* Hold the cyclic decomposition of the (multiple) replica
1263 gmx_bool bAnyReplicaExchanged = FALSE;
1264 *bThisReplicaExchanged = FALSE;
1266 for (i = 0; i < re->nrepl; i++)
1268 if (re->destinations[i] != re->ind[i])
1270 /* only mark as exchanged if the index has been shuffled */
1271 bAnyReplicaExchanged = TRUE;
1275 if (bAnyReplicaExchanged)
1277 /* reinitialize the placeholder arrays */
1278 for (i = 0; i < re->nrepl; i++)
1280 for (j = 0; j < re->nrepl; j++)
1282 re->cyclic[i][j] = -1;
1283 re->order[i][j] = -1;
1287 /* Identify the cyclic decomposition of the permutation (very
1288 * fast if neighbor replica exchange). */
1289 cyclic_decomposition(re->destinations, re->cyclic, re->incycle, re->nrepl, maxswap);
1291 /* Now translate the decomposition into a replica exchange
1292 * order at each step. */
1293 compute_exchange_order(fplog, re->cyclic, re->order, re->nrepl, *maxswap);
1295 /* Did this replica do any exchange at any point? */
1296 for (j = 0; j < *maxswap; j++)
1298 if (replica_id != re->order[replica_id][j])
1300 *bThisReplicaExchanged = TRUE;
1307 gmx_bool replica_exchange(FILE *fplog, const t_commrec *cr, struct gmx_repl_ex *re,
1308 t_state *state, gmx_enerdata_t *enerd,
1309 t_state *state_local, gmx_int64_t step, real time)
1313 int exchange_partner;
1315 /* Number of rounds of exchanges needed to deal with any multiple
1317 /* Where each replica ends up after the exchange attempt(s). */
1318 /* The order in which multiple exchanges will occur. */
1319 gmx_bool bThisReplicaExchanged = FALSE;
1323 replica_id = re->repl;
1324 test_for_replica_exchange(fplog, cr->ms, re, enerd, det(state_local->box), step, time);
1325 prepare_to_do_exchange(fplog, re, replica_id, &maxswap, &bThisReplicaExchanged);
1327 /* Do intra-simulation broadcast so all processors belonging to
1328 * each simulation know whether they need to participate in
1329 * collecting the state. Otherwise, they might as well get on with
1330 * the next thing to do. */
1331 if (DOMAINDECOMP(cr))
1334 MPI_Bcast(&bThisReplicaExchanged, sizeof(gmx_bool), MPI_BYTE, MASTERRANK(cr),
1335 cr->mpi_comm_mygroup);
1339 if (bThisReplicaExchanged)
1341 /* Exchange the states */
1342 /* Collect the global state on the master node */
1343 if (DOMAINDECOMP(cr))
1345 dd_collect_state(cr->dd, state_local, state);
1349 copy_state_nonatomdata(state_local, state);
1354 /* There will be only one swap cycle with standard replica
1355 * exchange, but there may be multiple swap cycles if we
1356 * allow multiple swaps. */
1358 for (j = 0; j < maxswap; j++)
1360 exchange_partner = re->order[replica_id][j];
1362 if (exchange_partner != replica_id)
1364 /* Exchange the global states between the master nodes */
1367 fprintf(debug, "Exchanging %d with %d\n", replica_id, exchange_partner);
1369 exchange_state(cr->ms, exchange_partner, state);
1372 /* For temperature-type replica exchange, we need to scale
1373 * the velocities. */
1374 if (re->type == ereTEMP || re->type == ereTL)
1376 scale_velocities(state, sqrt(re->q[ereTEMP][replica_id]/re->q[ereTEMP][re->destinations[replica_id]]));
1381 /* With domain decomposition the global state is distributed later */
1382 if (!DOMAINDECOMP(cr))
1384 /* Copy the global state to the local state data structure */
1385 copy_state_nonatomdata(state, state_local);
1389 return bThisReplicaExchanged;
1392 void print_replica_exchange_statistics(FILE *fplog, struct gmx_repl_ex *re)
1396 fprintf(fplog, "\nReplica exchange statistics\n");
1400 fprintf(fplog, "Repl %d attempts, %d odd, %d even\n",
1401 re->nattempt[0]+re->nattempt[1], re->nattempt[1], re->nattempt[0]);
1403 fprintf(fplog, "Repl average probabilities:\n");
1404 for (i = 1; i < re->nrepl; i++)
1406 if (re->nattempt[i%2] == 0)
1412 re->prob[i] = re->prob_sum[i]/re->nattempt[i%2];
1415 print_ind(fplog, "", re->nrepl, re->ind, NULL);
1416 print_prob(fplog, "", re->nrepl, re->prob);
1418 fprintf(fplog, "Repl number of exchanges:\n");
1419 print_ind(fplog, "", re->nrepl, re->ind, NULL);
1420 print_count(fplog, "", re->nrepl, re->nexchange);
1422 fprintf(fplog, "Repl average number of exchanges:\n");
1423 for (i = 1; i < re->nrepl; i++)
1425 if (re->nattempt[i%2] == 0)
1431 re->prob[i] = ((real)re->nexchange[i])/re->nattempt[i%2];
1434 print_ind(fplog, "", re->nrepl, re->ind, NULL);
1435 print_prob(fplog, "", re->nrepl, re->prob);
1437 fprintf(fplog, "\n");
1439 /* print the transition matrix */
1440 print_transition_matrix(fplog, re->nrepl, re->nmoves, re->nattempt);