This file was made on July 7, 2010 How to build GAMESS version 25 Mar 2010 (R2) with CHARMM (version?): This is example for 64 bit gnu platforms (gfortran) in parallel, but it might work with others, too. 1. Build a working parallel CHARMM first: install.com gnu xxlarge M x86_64 mpif90 2. unpack and untar the gamess-20100325.2-charmm.tar.gz file to some empty directory 3. copy all gamess/source files from GAMESS distribution to CHARMM source tree (mkdir source/gamint/gamess first): cp ~/gamess-orig/gamess/source/* source/gamint/gamess 4b. cp ddi.src source/gamint 4d. cp gukini.src source/gukint 4e. cp gamess.fcm source/fcm 4f. overwrite with the rest of files from this patch directory sources in the source/gamint/gamess directory cp *.src *.c source/gamint/gamess 5. copy gmscomp_gnu, actvte.f to the tool directory 6. copy gamess.mk to the build/gnu directory 7. replace the QUANTUM keyword in build/gnu/pref.dat with GAMESS 8. make sure that build/gnu/Makefile_gnu has -DLINUX64 in the CC line 9. add gamess.a line to the build/gnu/objlibs.mk or build/gnu/Makefile_gnu (older CHARMM versions) 9. rm -r lib build/gnu/*.mod 10. install.com gnu xxlarge M x86_64 mpif90 Depending on the CHARMM version you may experience some name clashes, ie the subroutine has the same name in the CHARMM and in the GAMESS. The fix is simply to rename the subroutines and corresponding calls in one of the programs (usually the one where the problem routine is in single file). Also depending on the version of CHARMM, XXLARGE executble can be quite big so one might need to compile with -mcmodel=medium, or reduce the number of pref.dat keywords.