From hommes%!at!%derioc1.organik.uni-erlangen.de Wed May 31 04:44:31 1995 Received: from faui45.informatik.uni-erlangen.de for hommes #at# derioc1.organik.uni-erlangen.de by www.ccl.net (8.6.10/930601.1506) id EAA18310; Wed, 31 May 1995 04:35:36 -0400 Received: from derioc1.organik.uni-erlangen.de by uni-erlangen.de with SMTP; id AA08387 (5.65c-7/7.3w-FAU); Wed, 31 May 1995 10:31:48 +0200 Received: from q650.organik.uni-erlangen.de by organik.uni-erlangen.de with SMTP; id AA07631 (5.64/7.4b-FAU); Wed, 31 May 95 10:30:05 +0200 Message-Id: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 31 May 1995 10:31:47 +0200 To: "Savant Ahmed" From: hommes \\at// derioc1.organik.uni-erlangen.de (Nico van Eikema Hommes) Subject: Re: CCL:MP2/6-311G** in G92 Cc: chemistry&$at$&ccl.net Hi Savant, >We are running an MP2/6-311G** calculation on a molecule C7H12 on an SGI >Indigo**2 machine using Gaussian92. >We have 190Meg swap space and 500Meg scratch space. Even when we use the Stingy >or the VeryStingy mode we still run out of scratch space. The MaxDisk is set at >400Meg and we are using the SCF=Direct. I fear that this system is too large for your machine. My experience with MP2 frequencies is that they use excessively large amounts of disk space. "Stingy" reduces the requirements only to some extent. I recently ran a MP2 freq. job with 135 basis functions, which required almost 2 Gb of scratch space (with the "stingy" keyword). Since yours is a 198 bf system, you'll probably need a multiple of that. A suggestion: look at what the sophisticated DFT methods tell you (use BLYP or Becke3LYP or Becke3P86). The results are often very similar to MP2 results. Best wishes, Nico van Eikema Hommes -- Dr. N.J.R. van Eikema Hommes Computer-Chemie-Centrum hommes ^at^ ccc.uni-erlangen.de Universitaet Erlangen-Nuernberg Phone: +49-(0)9131-856532 Naegelsbachstr. 25 FAX: +49-(0)9131-856566 D-91052 Erlangen, Germany