From chemistry-request- at -server.ccl.net Fri Jun 2 10:57:09 2000 Received: from ccl.net (atlantis.ccl.net [192.148.249.4]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id KAA29888 for ; Fri, 2 Jun 2000 10:57:09 -0400 Received: from mcmail.cis.McMaster.CA (mattacf-: at :-mcmail.CIS.McMaster.CA [130.113.64.66]) by ccl.net (8.9.3/8.9.3/OSC 2.0) with ESMTP id KAA27793 for ; Fri, 2 Jun 2000 10:56:56 -0400 (EDT) Received: from localhost (mattacf:~at~:localhost) by mcmail.cis.McMaster.CA with ESMTP id KAA00730 for ; Fri, 2 Jun 2000 10:56:42 -0400 (EDT) Date: Fri, 2 Jun 2000 10:56:42 -0400 (EDT) From: "C.F. Matta" To: CHEMISTRY-: at :-www.ccl.net Subject: Optimum memory allocation in GAUSSIAN94 Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Hello everybdy, In GAUSSIAN94, I noticed that the job CPU time as recorded in the log file increases when I allocate too much memory (instead of decreasing). For example, a geometry optimization of benzene at the restricted Hartree-Fock level using a 3-21G basis set on a LINUX 5.2 platform with a PENTIUM III 600MHz processor (768MBs RAM), took the following times: 200 MB ----> 1 minutes 18.5 seconds 600 MB ----> 2 minutes 11.6 seconds I noticed the same with other systems as well, larger memory=slower job. There must be a way to estimate the optimum memory allocation for a specific job. I would much appreciate your help. Thank you very much. (I will summarize) Cherif ___________________________________________________________________________ Cherif F. Matta tel. (905) 525-9140 ext. 22502 Chemistry Department fax (905) 522-2509 McMaster University _______________________ Hamilton, Ontario, CANADA L8S 4M1. | * "You'll always miss ....................................................| 100% of the shots you Member of the Board of Governors of the University | don't take".Anonymous ___________________________________________________________________________