From ec74f5259425aa6df35fbca95c018124d156f14a Mon Sep 17 00:00:00 2001
From: Berk Hess <hess@kth.se>
Date: Tue, 10 Jun 2014 14:38:04 +0200
Subject: [PATCH] Decoupled repl_ex_nst from nstcalcenergy

The replica exchange frequency is automatically changed by mdrun
to a multiple of nstcalcenergy, which is annoying. It turns out that
it doesn't need to be a multiple, so this changing has been removed.
Fixes #1494

Change-Id: I00833f92fd468924f61879aff8b7c85fe79d3c2e
---
 src/programs/mdrun/md.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/src/programs/mdrun/md.c b/src/programs/mdrun/md.c
index 60b01edd93..b7dab3cf20 100644
--- a/src/programs/mdrun/md.c
+++ b/src/programs/mdrun/md.c
@@ -191,7 +191,7 @@ double do_md(FILE *fplog, t_commrec *cr, int nfile, const t_filenm fnm[],
     int               count, nconverged = 0;
     real              timestep   = 0;
     double            tcount     = 0;
-    gmx_bool          bConverged = TRUE, bOK, bSumEkinhOld, bExchanged, bNeedRepartition;
+    gmx_bool          bConverged = TRUE, bOK, bSumEkinhOld, bDoReplEx, bExchanged, bNeedRepartition;
     gmx_bool          bAppend;
     gmx_bool          bResetCountersHalfMaxH = FALSE;
     gmx_bool          bVV, bIterativeCase, bFirstIterate, bTemp, bPres, bTrotter;
@@ -465,15 +465,6 @@ double do_md(FILE *fplog, t_commrec *cr, int nfile, const t_filenm fnm[],
         set_constraints(constr, top, ir, mdatoms, cr);
     }
 
-    if (repl_ex_nst > 0)
-    {
-        /* We need to be sure replica exchange can only occur
-         * when the energies are current */
-        check_nst_param(fplog, cr, "nstcalcenergy", ir->nstcalcenergy,
-                        "repl_ex_nst", &repl_ex_nst);
-        /* This check needs to happen before inter-simulation
-         * signals are initialized, too */
-    }
     if (repl_ex_nst > 0 && MASTER(cr))
     {
         repl_ex = init_replica_exchange(fplog, cr->ms, state_global, ir,
@@ -730,6 +721,7 @@ double do_md(FILE *fplog, t_commrec *cr, int nfile, const t_filenm fnm[],
     bStartingFromCpt = (Flags & MD_STARTFROMCPT) && bInitStep;
     bLastStep        = FALSE;
     bSumEkinhOld     = FALSE;
+    bDoReplEx        = FALSE;
     bExchanged       = FALSE;
     bNeedRepartition = FALSE;
 
@@ -792,6 +784,9 @@ double do_md(FILE *fplog, t_commrec *cr, int nfile, const t_filenm fnm[],
                             && (ir->bExpanded) && (step > 0) && (!bStartingFromCpt));
         }
 
+        bDoReplEx = ((repl_ex_nst > 0) && (step > 0) && !bLastStep &&
+                     do_per_step(step, repl_ex_nst));
+
         if (bSimAnn)
         {
             update_annealing_target_temp(&(ir->opts), t);
@@ -1021,7 +1016,7 @@ double do_md(FILE *fplog, t_commrec *cr, int nfile, const t_filenm fnm[],
 
         do_ene = (do_per_step(step, ir->nstenergy) || bLastStep);
 
-        if (do_ene || do_log)
+        if (do_ene || do_log || bDoReplEx)
         {
             bCalcVir  = TRUE;
             bCalcEner = TRUE;
@@ -1812,8 +1807,7 @@ double do_md(FILE *fplog, t_commrec *cr, int nfile, const t_filenm fnm[],
 
         /* Replica exchange */
         bExchanged = FALSE;
-        if ((repl_ex_nst > 0) && (step > 0) && !bLastStep &&
-            do_per_step(step, repl_ex_nst))
+        if (bDoReplEx)
         {
             bExchanged = replica_exchange(fplog, cr, repl_ex,
                                           state_global, enerd,
-- 
2.22.0