Subject: CCL: ESP fit and symmetry in G98

From: "Petr Toman" <[email-masked]>
Date: Mon, 21 Aug 2000 12:21:50 +0200

Dear CCL members,
I am calculating the atomic charges of some symmetric molecules by means 
of the Merz-Kollman fitting. The conformations as well as the density 
matrices are symmetric, but the resulting MK charges are completely 
asymmetric (the differences are more than 0.2 !!!). 
Does anybody know the reason?

It seems that using a higher point density by means of IOp(6/41=10,6/42=17)
helps a bit. 
I tried also IOp(6/41=20,6/42=35) but in this case an error occurred:

  287560 points will be used for fitting atomic charges
 Fitting point charges to eletrostatic potential
 Convergence failure in SVDSol.
 Error termination via Lnk1e in /software/g98-a7/sgi_65/g98/l602.exe.

Does anybody know how can I control the convergence in SVDSol (maybe some 
limit of the number of steps)?

Thank you in advance for any help.

Yours, 
Petr Toman