Subject: 64-bit machines in computational chemistry

From: Daniel Svozil <[email-masked]>
Date: Tue, 25 Feb 2003 16:26:36 +0100

Dear All,

our group is  going to buy a 64-bit multiprocessor server (8 CPUs, 32 GB of memory). We narrowed down our considerations to three architectures, but apart from performance we also take into considerations the availability of the software.

We are considering the following three architectures:

Compaq Alpha EV7 (Tru64, OpenVMS or Linux???)
IBM Power 4+ (IBM p650, AIX 5.2 system) 
Intel Itanium 2 (SGI Altrix 3000, Red Hat 7.2 Linux system)

We use the following codes: Gaussian 98, Molpro, Molcas, Turbomole,
Gromos, Charmm, Gamess. I've already asked the authors of the individual
packages on their availability on different platforms.

I'd like to know you experience with using 64-bit machines in
computational chemistry. Which of those machines would you recommend?

And which operating system+compiler (both Fortran and C/C++)? The speed of the code also depends on the BLAS implementation, do you have any experience with it? Also, do
you have any knowledge of the quality of 64-bit compilers (I've heard
e.g. that Intel Compiler, possibly the only solution for Linux IA64, is still
a bit buggy).

Here are my comments on the individual architectures

1) Alpha
- expensive (comparing to Itanium 2 based systems)
- not very clear future of Alpha processor

2) IBM Power 4+
- low memory bandwidth
- a bit expensive

3) Itanium 2
- Itanium 1 was a big dissapointment, so I am still a bit diffident of
  Intel
- quality of Intel Compilers (Fortran and C/C++) for Linux ?????

Any comments are very welcome.

Thanks in advance

Dan Svozil

-- 
Daniel Svozil, PhD
Institute of Organic Chemistry and Biochemistry
and Center for Complex Molecular Systems and Biomolecules
http://www.molecular.cz/
Czech Republic

phone: +420-2-20 183 263