From owner-chemistry@ccl.net Fri Jan  5 06:08:01 2007
From: "Cory Pye cpye[]crux.smu.ca" <owner-chemistry###server.ccl.net>
To: CCL
Subject: CCL:G: G03:freq calculations
Message-Id: <-33331-070104191957-17120-SgnnlJ1vuYmegTKSZCjMEw###server.ccl.net>
X-Original-From: Cory Pye <cpye_-_crux.smu.ca>
Content-Type: TEXT/PLAIN; charset=US-ASCII
Date: Thu, 4 Jan 2007 19:38:39 -0400 (AST)
MIME-Version: 1.0


Sent to CCL by: Cory Pye [cpye*o*crux.smu.ca]
Hello,

I seem to recall that there is a utility in Gaussian called freqmem that you
can use to calculate the optimum amount of memory for your particular system. I
think it works for HF (and possibly B3LYP as well). If this value is less than
the amount of physical memory on your computer, than you can use it. I
routinely use %mem=512Mb, which on a shared-use 10 processor SMP with 5Gb
memory running in serial mode seems to work fine.

-Cory

On Wed, 3 Jan 2007, errol lewars elewars:trentu.ca wrote:
>
> You  did not say what your molecule is or what your program is (it looks
> like Gaussian). If applicable, you could try running the molecule within
> its symmetry (rather than ignoring symmetry). You could also try using
> more (or less!) memory and see what happens.
>
> Very long times for frequencies are "reasonable".
>
> soumya s soumya_samineni_._rediffmail.com wrote:
>
> >Dear people,
> >Naive question ... sry.
> >I try to run a freq calculation on porphyrin
> >
> >%nproc=8
> >%mem=8MW
> >opt freq b3lyp/6-31g* nosymm
> >
> >0 1
> >
> >and the frequency calculation took almost 10hrs (is this resonable!!).. how can i make the calculations run better (other than increasing the no. of procs..)
> >

   *************    !  Dr. Cory C. Pye
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