Subject: Summary: Different platforms for QM ...

From: Emad Tajkhorshid <[email-masked]>
Date: Tue, 14 Nov 2000 12:52:46 -0600 (CST)

Dear all,

I would liek to thank all people who replied to my question. here is a
summary.

Original Question:

> I wonder if anybody has efficiently used SUN platforms for running quantum
> chemical calculations, e.g. Gaussian9x. We are considering to purchase a
> new machine for our group particularly for quantum chemical calculations.
> Among our options are SUN and Alpha machines. Any comment or suggestion
> with regard to this is appreciated.
>
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Date: Thu, 09 Nov 2000 01:26:46 -0500
From: Deepak Singh <[email-masked]>

We have had success running G94 on DEC-alpha machines.  They were very fast.
However, in my opinion alphas are not the most stable platform.  While I have
never used SUNS the reports are fairly good.  A SUN ULTRA10 is a good machine to
invest in.
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Date: Thu, 9 Nov 2000 08:59:23 +0100
From: Jens Abildgaard <[email-masked]>

The sun machines usually sucked, but it has been a while since we tested
them, so please send us details when you find out. Solaris  (64 bit?) and
UltraSpark (64 bit) with the "switched crossbar technology should on paper
run well, but I have just never heard of anybody achiving that.

I would consider IBM (Power3 chip!!!, and not the PowerPC running AIX) or HP
(PA-RISC 8600 or similar with 64 bit HP-UX 11.0, and MLIB mathematical
libraries). Remember to look at Prize/Performance, if you can afford it at
all.

Be aware that if you test LINUX boxes, you need a reasonable size problem,
as small testjobs run very fast, while real size problems may easyly be a
factor of 10 slower than the real UNIX machine
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Date: Thu, 9 Nov 2000 09:58:30 +0100 (MET)
From: Frank Jensen <[email-masked]>

        I would be interested in knowing if anybody has
a working SUN version of Gaussian-94 still around.
I do have both Gaussian-98 and -94, but they are giving
me some discrepancies in the SGI version. I have G98 
running on a SUN machine, but the makefile for
G94 is set up for SUN-OS 5 and compiler version 2, and I
don't have access to that kind of vintage machines.
Thus I would be interested in either a working set of
executables for G94, or a G94 makefile for the more
recent SUN-OS (7/8) and compilers (5/6).
****************************************************************************

Date: Thu, 9 Nov 2000 09:48:05 +0000 (GMT)
From: Bruce. Tattershall <[email-masked]>

Our university has several timeshared Sun multiprocessor machines running
unix.   Details may be found at http://www.ncl.ac.uk/ucs/computers.html
We have used g94 and now g98 on these, essentially using spare capacity
via dnqs.  Performance is excellent for my purposes:  geometry optimisation
of a 67 atom molecule with no symmetry (39 non-H atoms, including a P4S3
cage and four fused organic rings) took 4 days of cpu time using one 
processor of the fastest of these, at the MPW1PW91/Ahlrichs SVP level.
Considerable experiment or expertise is needed to screw up the optimisation
level by using appropriate compilation parameters, to achieve this on a
particular installation.   We have found that support from Gaussian leaves
quite a bit to be desired:  in particular, while the main suite of Gaussian
routines work as intended, we believe, several of the utility programs, 
e.g. formchk, do not work at all.  These are installation-dependent bugs
which Gaussian has said they will work on, but as far as we know, still have
not cured.
****************************************************************************

Date: Thu, 09 Nov 2000 07:09:43 +0000
From: [email-masked]

Any predujices against Athlon or Intel machines?  An 800MHZ PIII Dell costs
~$1400,
and runs Gaussian just fine.

John McKelvey
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Date: Thu, 10 Nov 2000 11:32:21 -0500 (EST)
From: Sergei Tretiak <[email-masked]>

Dear Emad,

I have some experience of running G9X on Alpha (dual 21264 666 MHz box), 
PC (dual Intel PIII 800 MHz box) and Sun (4-CPU 600MHz box). My 
impression is:

1. Alpha is the champ. It is in average 1.5 times faster then Sun and has 
reasonable price/performance ratio; easy to configure and compile G9X. Go 
for Linux box with Compaq compiler suit. It performance is on par with 
native Unix64 OS (but a lot cheaper).

2. PC is extremely fast and extremely cheap. Its speed is on par with Sun 
and PC has the best price/performance ratio. However, building PC 
requires carefull choice of hardware (e.g. SCSI configuration, good motherboard
and 
memory, etc.) and software (e.g. PGI compiler and optimized BLAS for G9X 
compilation). Also PC has limit on RAM (about 1-1.5 GB) and # of CPUs (2).

3. There is no reason to buy Sun for quantum chemical calculations 
(unless there are other motives). It is not faster then PC and very 
expensive. Compilation of G9X could be a headache. 
****************************************************************************

Emad
------------------
Emad Tajkhorshid                  http://www.ks.uiuc.edu/~emad 
Theoretical Biophysics Group
Beckman Institute for Advanced Science and Technology 
405 N. Mathews, Urbana, IL 61801
Tel: (217)244-5042  Fax: (217)244-6078 Email: [email-masked]