Subject: A couple of questions about AIM analysis

From: Gary Breton <[email-masked]>
Date: Thu, 14 Mar 2002 14:05:12 -0500

Hello all,

I have implemented AIM analysis from with Gaussian98W successfully many
times.  The keywords I use are: SCF(conver=8) density=current
AIM=bondorders.  The level of theory in all cases has been
RB3LYP/6-311+G(2d,p) which is the same level of theory as the other
calculations involving these molecules (e.g., minimizations, frequency
calculations, NBO analysis).

However,when attempting the same calculation on one particular structure,
the calculation fails.  I am given the information below:

 WARNING: RMS ERROR HAS INCREASED
 WARNING: RMS ERROR HAS INCREASED
 WARNING: RMS ERROR HAS INCREASED
 WARNING: RMS ERROR HAS INCREASED
 NEWTON STEP FAILED FOR SURFACE SHEET  16
 Error termination via Lnk1e in C:\G98W\l609.exe.
 Job cpu time:  0 days  4 hours 16 minutes  8.0 seconds.
 File lengths (MBytes):  RWF=   48 Int=    0 D2E=    0 Chk=    2 Scr=    1

The Gaussian User's Reference suggests that the AIM code will fail at times
and cites the particular instance when the message NEWTON-RAPHSON STEP
FAILED is due to a molecule with rings that has an unusual topology (which
may well be the case).  Is there any cure for this problem?  Am I able to
tweak something to get the calculation to go to completion?

Many thanks for your help in advance,

Gary W. Breton
Chair and Associate Professor
Department of Chemistry
Berry College
PO Box 495016
Mount Berry, GA 30149

"There's a light at the
end of the tunnel, but it
may be an oncoming train"