Subject: Optimum memory allocation in GAUSSIAN94

From: "C.F. Matta" <[email-masked]>
Date: Fri, 2 Jun 2000 10:56:42 -0400 (EDT)

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 
___________________________________________________________________________