From owner-chemistry@ccl.net Sat Nov 14 00:29:00 2009 From: "Heath Watts hdw115{}psu.edu" To: CCL Subject: CCL:G: MaxDisk algorithms in Gaussian 03 Message-Id: <-40680-091113141401-18376-IvAJbr+Q0jbpCp5LDjYSvA-.-server.ccl.net> X-Original-From: Heath Watts Content-Type: multipart/alternative; boundary=00151759031edb9ede0478448e3e Date: Fri, 13 Nov 2009 13:09:16 -0500 MIME-Version: 1.0 Sent to CCL by: Heath Watts [hdw115:+:psu.edu] --00151759031edb9ede0478448e3e Content-Type: text/plain; charset=ISO-8859-1 Hello, I recently made the mistake of using MaxDisk while doing some DFT calculations in Gaussian 03. When I repeated the calculations without using MaxDisk, the calculated frequencies were different, and the electronic energy was slightly different than those calculated using MaxDisk. Was my use of MaxDisk with DFT completely invalid, and should I discard my results > from those calculations, or is there any meaning to my results? When applying MaxDisk to methods like MP2, Gaussian 03 is forced to use a different optimization algorithm, based on the scratch space indicated by MaxDisk. Does allocation of different amounts of MaxDisk space change not only the algorithm used, but the energy and frequency results obtained? Does Gaussian 03 also change its optimization algorithm when using MaxDisk with DFT methods? I've been unable to find references pertinent to this issue. Thanks for your time and help. Best, Heath --00151759031edb9ede0478448e3e Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hello,
I recently made the mistake of using MaxDisk while doing some DFT= calculations in Gaussian 03. When I repeated the calculations without usin= g MaxDisk, the calculated frequencies were different, and the electronic en= ergy was slightly different than those calculated using MaxDisk. Was my use= of MaxDisk with DFT completely invalid, and should I discard my results fr= om those calculations, or is there any meaning to my results? When applying= MaxDisk to methods like MP2, Gaussian 03 is forced to use a different opti= mization algorithm, based on the scratch space indicated by MaxDisk. Does a= llocation of different amounts of MaxDisk space change not only the algorit= hm used, but the energy and frequency results obtained? Does Gaussian 03 al= so change its optimization algorithm when using MaxDisk with DFT methods?= =A0 I've been unable to find references pertinent to this issue. Thanks= for your time and help.
Best,
Heath
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