********> bugfix 6
Author: Ross Walker
Date:   01/14/09

Programs: Ptraj

Description: Ptraj can fail to identify some newer CHARMM PSF files
             such as those labelled as PSF CMAP but without the
             CHEQ flag. This should correct this problem.

Use the following patch to update $AMBERHOME/src/ptraj/ptraj.c

---------------------------------------------------------------------------
--- ptraj.c     2009-01-14 08:50:33.000000000 -0800
+++ ptraj.c     2009-01-14 09:12:08.000000000 -0800
@@ -3036,11 +3036,18 @@

   /*
    *  check to see if the file has "PSF" or "PSF " as the header
-   *  or "PSF CMAP CHEQ" as seen in newer charmm psfs.
+   *  Examples of CHARMM file headers are:
+   *  PSF
+   *  PSF CMAP
+   *  PSF CMAP CHEQ
    *  indicating a CHARMM PSF file, load it and return...
    */
+  /* Look for "PSF\n" or "PSF " - we do this separately since
+   * It can help with false positives if we just searched for
+   * PSF for example.
+   */
   if ( strcmp(buffer, "PSF \n") == 0 ||
-       strcmp(buffer, "PSF\n") == 0 || strcmp(buffer, "PSF CMAP CHEQ\n") == 0) {
+       strncmp(buffer, "PSF ", 4) == 0 ) {
     state = loadCharmmPSF(fp, 1);
     *statep = state;
     return;
---------------------------------------------------------------------------
Workarounds: Edit the header of your PSF to read PSF CMAP CHEQ