Subject: Re: CCL:Spartan job failure

From: "Wayne Huang" <[email-masked]>
Date: Mon, 13 May 1996 09:01:59 -0700

On May 10, 10:45am, Konstantin Momot wrote:
> I am trying to run a single point energy calculation on a
> metalloporphyrin complex using PM3(tm).  The molecule contains 137 atoms,
> see attached output file.  The job crashes for no apparent reason after
> some time that may range from 1hr to several hrs of CPU time ...

Regarding your question on Spartan job failure, by browsing your output file,
this seems to be a SCF convergence problem on your imported structure. Without
further exploring your calculation, there are a few ways of handing SCF
converence on SE methods:

(1) Use keyword NOPSEUDO, this switches off pseudodiagonalization which works
    quite well in many cases;

(2) Use keyword DAMP=0.75, GRADUAL and DIIS=5 which are available on
    convergent button;

(3) Since your system is radical cation, you could also try to converge the
    alternative state first (different Multiplicity/charge) and use it as
    guess to restart your final calculation;

(4) Inspect your structure and alter the initial geometry slightly. This might
    also help to converge.

Hope these help. Convergence problem is not uncommon on large structure
like this and it does need bit of tailoring to make it work. I might look into
your structure more carefully and give you further comments.

Have a good one!

--Wayne

-- 
+---------------------------------------------------------------+
|  Wayne Huang, Ph.D.    	|  18401 Von Karman, Suite 370  | 
|  Computational Chemist 	|  Irvine, California 92715     |
|  Wavefunction, Inc.    	|  714-955-2120 <> 955-2118(fax)|  
|  [email-masked]     	|  Web: http://www.wavefun.com  |
+---------------------------------------------------------------+