Subject: Gaussian-98 efficiency for DFT calculations (repeated)

From: "Ivan I. Oleinik" <[email-masked]>
Date: Wed, 24 Mar 1999 12:25:12 +0000 (GMT)

I posted the message below on Monday, got automated confirmation that it
will be distributed on Tuesday but did not get any mail from CCL in the
last couple of days. The interesting thing that I have already started to
receive replies on the question which I thought was not mailed. I think
system has some (geographical) selectivity in distributing the CCL
messages. I post my question again. 

Ivan Oleinik
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Hello,

I am a novice user of Gaussian and want to have a good advice from
experts on tuning Gaussian-98 options to get best performance in terms of
CPU time. 

Some specific information:

1. Molecular system:  medium-size hydrocarbon clusters (20-30 carbon
atoms) 

2. Method: DFT (standard LSDA + Becke-Perdew-Wang gradient corrections). 

3. Task: energy and forces with moderate accuracy.

4. System: SGI O2K machine with plenty of memory available. 

I can get trivial speedup by using several processors in parallel mode,
but I want to tune the execution on the level of single processor first.
Also the effect of the basis set size is also obvious and predictable.

Since I have to sample quite a large number of configurations studying
transition states, I have to count every CPU minute. But according to my
little experience Gaussian is still slow as compared to MSI DMOL. 

I will summarize responses,

Ivan Oleinik.

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Ivan I. Oleinik                 E-mail : [email-masked]
Department of Materials
University of Oxford
Parks Road
Oxford OX1 3PH                     Tel : +44 (0)1865 283325
United Kingdom                     Fax : +44 (0)1865 273764 
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