CHARMM Development Project Forums CHARMM Community Bug Reports & Fixes 64-bit gfortran fix for Mac OS X 10.6

For compiling recent CHARMM releases (c34 and later) on Mac systems running OS X 10.6 (Xcode 3.2.2, gfortran 4.5 from http://hpc.sourceforge.net), I found the following two changes were needed for e.g.

./install.com osx xlarge x86_64 gfortran

(1) install.com, in "case osx:" section, for trajectory compatibility change

    else
        echo "GNU"      >! $chmbuild/pref$$.dat
        echo "GFORTRAN"   >>! $chmbuild/pref$$.dat
    endif

to add the I4BINARY pref.dat keyword

    else
        echo "GNU"      >! $chmbuild/pref$$.dat
        echo "GFORTRAN"   >>! $chmbuild/pref$$.dat
        if( $longint == 1 ) then
            echo "I4BINARY"   >>! $chmbuild/pref$$.dat
        endif
    endif

and (2) in build/UNX/Makefile_osx, ca. line 64, change

    else
      FFLAGS := $(FFLAGS) -march=pentium3 -mtune=pentium3
    endif
    FC = $(FCOMPILER) -DGNU $(FFLAGS)
    LD = $(FCOMPILER) -O2 $(FFLAGS)

to make 8-byte integers the default for 64-bit via

    else
      FFLAGS := $(FFLAGS)
    endif
    ifdef X86_64
      FC = $(FCOMPILER) -DGNU $(FFLAGS) -fdefault-integer-8
      LD = $(FCOMPILER) -O2 $(FFLAGS) -fdefault-integer-8
    else
      FC = $(FCOMPILER) -DGNU $(FFLAGS)
      LD = $(FCOMPILER) -O2 $(FFLAGS)
    endif