********>bugfix.7:
Author: Daniel R. Roe
Date: 06/17/2008

Programs: sander

Description: When running replica exchange with nmr weight restraints 
             (nmropt>0), the bath temperature (temp0) would be reset to
             its initial value after every exchange, regardless of 
             whether an exchange was successful or not. This patch forces
             a re-read of the temp0 value after every exchange.

Affected files: src/sander/nmr.f , src/sander/remd.f 

Fix: Run this patch from the $AMBERHOME directory, with:
     $ patch -p0 -N -r patch_rejects < bugfix.7 

------------------------------------------------------------------------------

diff -Naur oldamber10/src/sander/nmr.f newamber10/src/sander/nmr.f
--- src/sander/nmr.f	2008-06-17 14:43:30.000000000 -0400
+++ src/sander/nmr.f	2008-06-17 15:13:07.000000000 -0400
@@ -1818,6 +1818,12 @@
    !  WEIGHT(23) : Exponential decay time constant for time-averaged plane-plane restraints
    !  WEIGHT(24) : The value of the LES target temperature on the first call
    use constants, only : one
+#ifdef MPI
+   ! initmodwt forces modwt() to re-read values such as temp0 - 
+   ! otherwise they will be reset to the initial value after each 
+   ! exchange.
+   use remd, only : initmodwt
+#endif
    implicit none
    
    integer jweit
@@ -1896,8 +1902,12 @@
    ! ICHOLD(I)=1, if weight of term was set to non-unity as of the previous call.
    ! ICHOLD(I)=2, if weight of term has been set to 0, or if the weight
    !              of the term is constant throughout the run (NSTEP1=NSTEP2=0).
-   
+
+#ifdef MPI
+   if (ionce /= 99.or.initmodwt) then
+#else   
    if (ionce /= 99) then
+#endif
 
       ichold(1:jweit) = 0
       weight(1:13) = ONE
@@ -1914,6 +1924,9 @@
       weight(24) = tauave(6)
       weight(25) = temp0les
       ionce = 99
+#ifdef MPI
+      initmodwt = .false.
+#endif
 
    end if
    ivdw = 0
diff -Naur oldamber10/src/sander/remd.f newamber10/src/sander/remd.f
--- src/sander/remd.f	2008-06-17 14:50:48.000000000 -0400
+++ src/sander/remd.f	2008-06-17 15:08:49.000000000 -0400
@@ -59,7 +59,10 @@
 !                     during hybrid remd.
 !   jumpright       - if true replica that controls the exchange will attempt
 !                     to exchange with the replica at next highest temperature.
-logical, save :: jumpright, hybridwritetraj
+!   initmodwt       - If nmropt>0 modwt will reset temp0 to its initial value
+!                     after each exchange. initmodwt will force a re-read of
+!                     temp0 after each exchange.
+logical, save :: jumpright, hybridwritetraj, initmodwt
 
 ! ... integer variables:
 ! mdloop      - Current exchange index. mdloop will be always 0 unless rem>0
@@ -174,6 +177,7 @@
    myscaling = -1.0d0
    newtargettemp = -99.0d0
    jumpright = .true.
+   initmodwt = .true.
    rremd_idx=-1
    ! For storing ekmh between runmd calls
    ! DAN ROE: ntt==1 only?
@@ -413,6 +417,11 @@
    ! DAN ROE: Eventually take out debug info.
    call remd_scale_velo(v,temp0,nr,nr3)
 
+   ! initmodwt forces modwt() in nmr.f to re-read values such as temp0 - 
+   ! otherwise they will be reset to the initial value after each 
+   ! exchange.
+   initmodwt = .true.
+
    return
 
 end subroutine remd_exchange
------------------------------------------------------------------------------

Temporary workarounds: none