Subject: Re: CCL:gaussian 03 on macintosh

From: Gert von Helden <helden~at~fhi-berlin.mpg.de>
Date: Thu, 8 Apr 2004 10:32:20 +0200

dear all,
MacOSX is just another regular UNIX and one can compile the standard 
g03 source code on that machine (and optimize for the G5!). I did so 
and it runs very fast. On a typical DFT job, it is 2-3 times (yes, 
that much!) faster than on a Xeon (comparing a single 2 GHz Xeon CPU 
to a single 2 GHz G5 CPU).
For visualization, I use mostly viewmol, an excellent program for 
looking at molecules, vibrations, orbitals.... Added advantage: its 
free.

There are a couple of points to consider if you want to compile g03 on MacOSX:
I used the IBM xlf compiler (8.1 beta). The final version of the 
compiler is available now, I am about to order that one. It order to 
compile, you need a UNIX filesystem partition on the disk where g03 
is compiling, as hfs and hfs+ are not really case sensitive and in 
the preprocessor stage of the compilation (cpp), it needs to 
distinguish between xxxx.F and xxxx.f. The makefile is a hybrid of 
the rs6k.make and the linux makefile. I also added a few lines of 
fortran code and slightly modified some c source files (only on some 
files in the bsd subdir). Of course one has to keep in mind that the 
byteorder on a PowerPC is different from Intel and that, although the 
CPU is 64 bit, MacOSX is not (no support for 8 byte pointers). I also 
used the Apple BLAS (veclib).

The resulting code runs very well, 16 GB scratchfiles are no problem 
(no need to segment into 2 GB chunks). Bigger scratchfiles do not 
work, I guess the reason are the 4 byte pointers.

I tried to compile it for 2 CPUs (using openMP). That did not work 
and since I don't care, I gave up quickly. My feeling is that after 
spending some time, that would work as well.

Good luck,
Gert

At 16:53 +0200 7/4/04, Andreas Serr wrote:
>Dear all,
>
>we are considering using Gaussian 03 on a Mac OS X
>system. Has anybody experience in that field? In
>particular:
>
>- G03M is not optimised for Mac G5 architecture, so
>does it make sense to run it on G5 rather than on G4?
>
>- is GaussView M working fine with G5 computers?
>
>- does anyone have experience/benchmark tests for
>Gaussian running on Mac (G5/G4/...) in comparison
>with Gaussian on Intel Xeon-dual process. @ 2 GHz
>(Linux system)
>
>Regards,
>Andy
>
>andreas.serr~at~uni-bielefeld.de
>
>
>
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-- 
-------------------------------------
Gert von Helden
Fritz-Haber-Institut der Max-Planck-Gesellschaft
Faradayweg 4-6
14195 Berlin
tel.: +49-30-8413 5615
fax: +49-30-8413 5603