From: Berk Hess <hess@kth.se>
Date: Mon, 16 Jun 2014 07:17:35 +0000 (+0200)
Subject: Fixed sign error in posres dvdl
X-Git-Url: http://biod.pnpi.spb.ru/gitweb/?a=commitdiff_plain;h=239fe4f4e359533215dd7c2c1815e53f85751686;p=alexxy%2Fgromacs.git

Fixed sign error in posres dvdl

For position restraints the sign of the contribution of the change
in reference location was incorrect. Note that the contribution of
the change in force constant was and is correct.

Fixes #1408.

Change-Id: I75210c3855d13fdd58e0a698d6c5d7c7116f456b
---

diff --git a/src/gmxlib/bondfree.c b/src/gmxlib/bondfree.c
index 2c25351ec2..e9f68b3c10 100644
--- a/src/gmxlib/bondfree.c
+++ b/src/gmxlib/bondfree.c
@@ -2297,7 +2297,7 @@ real posres(int nbonds,
             vtot       += 0.5*kk*dx[m]*dx[m];
             *dvdlambda +=
                 0.5*(pr->posres.fcB[m] - pr->posres.fcA[m])*dx[m]*dx[m]
-                -fm*dpdl[m];
+                + fm*dpdl[m];
 
             /* Here we correct for the pbc_dx which included rdist */
             if (bForceValid)