

Whoops.  In the mail I sent you earlier, I said we had tried G2 on 
quinone energies.  That was a bit wrong.  We sis try it, but did not
have the computing resources to complete the jobs (which includes 
an 8 processor IBM/SP2 with 512MB/processor).

The method that we did use and get poor results from was the CBS-4 
calculation.  Sorry about the confusion.

Anthony Grafton
Department of Chemistry 
University of Oklahoma

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From: "Frederick R. Bennett" <[email-masked]>
Subject: CCL:G:G2 with reduced basis sets

Hi,
   someone was asking about attempting G2 calculations with reduced basis
sets. Well I found a paper addressing this issue exactly

 Gaussian-2 (G2) theory: Reduced basis set requirements, Curtis, Redfern,
Smith,  and Radom: JCP, 104 (13) 5184

Hope this helps

Ciao

===============================================================================
                    Frederick R. Bennett
                    
 Papernet Address:  Institut Fur anorganische, analytische 
                    und physikalische Chemie                  
                    Freiestrasse 3
                    CH-3000 Bern 9 
                    Switzerland
                    
 Mouthnet Address:  [41] (031) 631 4231

 Faxnet Address     [41] (031) 631 3994
 
 Internet Address:  [email-masked]

===============================================================================
From: Anthony P Scott <[email-masked]>
(also thanks to James W Gauld <[email-masked]>)

Jeremy,

I understand that James has already sent you two references for the 
G2(MP2,SVP) method.

Here are the two leading references for G2(MP2,SVP).

Smith, B. J. and Radom, L. J. Phys. Chem. 99 (1995) 6468.
        - where it is first introduced
Curtiss, L. A., Redfern, P. C., Smith, B. J. and Radom, L. J. Chem. Phys.
104 (1996) 5148.
        - a detailed description of G2(MP2,SVP), including the new HLC to 
use.

In your email you didn't say why the qcisd(t)/6-311g** calculataions are 
not possible.

Is it disk space or cpu time that limits you?

If you are trying to do these calculations with Gaussian you are really 
beating your head against a brick wall. Two other programs are 
substantially more efficient that G94 for these type of calculations.

Molpro96 ( limited to closed shell however) or ACES2 will result in 
(usually) much better cpu times that G94. They both make explicit use of 
symmetry, however ACES2 in C1 symmetry will often take longer than gaussian!!

If it is disk space that is the problem then try to get more!

Hope this is of some use.

Kind Regards,

Tony

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