********> bugfix.38
Correction Author: David A. Pearlman
Correction Date: 4/02/92  

Programs: SANDER

Severity: serious

Problem: 

       When running a restrained MD simulation with SANDER where the following
       conditions are met:

         1) The user has requested that the final restraint violations 
            will be written to a LISTOUT file.

         2) The total MD simulation is being run in multiple "segments"
            (NRUN > 1);

       then the final restraint violations in the requested LISTOUT file
       will not correspond to the violations on the final step of the
       simulation. They will be the violations on the final step of the
       first segment of the MD trajectory (i.e. the NSTLIMth step on the
       NRUN=1 leg). 

       The actual final deviations will appear in whatever file is
       assigned by default to unit 33 on the host computer. The behavior
       if a default unit 33 file already exists will be system dependent.

       This problem will only arise if NRUN>1 and a file redirection statement
       LISTOUT=filename (filename.NE.POUT) has been provided.
 
       This bug affects only the values in the LISTOUT file. The trajectory,
       any stored/restart coordinates, and any deviation information printed
       in the standard formatted output file will be correct.

Affects: 

       The restraint violation values in the requested LISTOUT file will be
       incorrect. If a LISTOUT=POUT command was given (print deviations in
       the formatted standard output file), the deviations will be correct.

Cause: 

       To avoid losing part of the restraint violations file during a system
       crash, the file is closed after it is written, at the end of
       every NSTLIM steps (thus forcing the write buffer to be cleared to
       disc). But because of an improperly constructed IF-BLOCK of code,
       the file was not being re-opened on subsequent writes.

Fix:  Make the following changes; see 0README for an explanation of the
      diff format.

***To routine NDVPRT in src/sander/ndvprt.f:
-------------------------------------------------------------------------

*** OLD ndvprt.f
--- NEW ndvprt.f
***************
*** 126,132
  C user-defined redirection).
  C
        IUSE = IOUT
-       IF (ITIMES.EQ.0) THEN
            IF (IREDIR(2).EQ.0) THEN
                RETURN
            ELSE

--- 126,131 -----
  C user-defined redirection).
  C
        IUSE = IOUT
            IF (IREDIR(2).EQ.0) THEN
                RETURN
            ELSE
***************
*** 140,146
                ELSE IF ((IREDIR(1).EQ.IREDIR(2) .AND.
       *                 REDIR(1)(1:IREDIR(1)).EQ.REDIR(2)(1:IREDIR(2)))
       *                 .OR. ITIMES.GT.0) THEN
!                   CALL OPNMRG(REDIR(2)(1:IREDIR(2)),ISCOPN,1,IOUT,IERR)
                    IF (IERR.EQ.1) RETURN
                ELSE
                    CALL OPNMRG(REDIR(2)(1:IREDIR(2)),ISCOPN,0,IOUT,IERR)

--- 139,145 -----
                ELSE IF ((IREDIR(1).EQ.IREDIR(2) .AND.
       *                 REDIR(1)(1:IREDIR(1)).EQ.REDIR(2)(1:IREDIR(2)))
       *                 .OR. ITIMES.GT.0) THEN
!                   CALL OPNMRG(REDIR(2)(1:IREDIR(2)),ISCOPN,2,IOUT,IERR)
                    IF (IERR.EQ.1) RETURN
                ELSE
                    CALL OPNMRG(REDIR(2)(1:IREDIR(2)),ISCOPN,0,IOUT,IERR)
***************
*** 147,153
                    IF (IERR.EQ.1) RETURN
                END IF
            END IF
-       END IF
  C
        WRITE(IOUT,9020) REDIR(2)(1:IREDIR(2))
        IUSE = ISCOPN

--- 146,151 -----
                    IF (IERR.EQ.1) RETURN
                END IF
            END IF
  C
        WRITE(IOUT,9020) REDIR(2)(1:IREDIR(2))
        IUSE = ISCOPN

-------------------------------------------------------------------------
Temporary workarounds: 

     Depending on the system, you may be able to recover the final restraint
     violations in the file which is assigned by default to unit 33.

Routines affected:

     SANDER  Routine NDVPRT in  .../amber4/sander/ndvprt.f