Subject: Re: CCL:Charges/bond-breaking

From: Ross Underhill <[email-masked]>
Date: Tue, 25 Apr 1995 09:04:37 -0400

The simple answer to your question is unrestricted HF theory.  The
complicated answer is to do a lot of CI.  The problem is that as you pull
the atoms apart you go through a singlet to triplet transition.  As the
atoms separate further the spins on the atoms becom uncorrelated and you
have basicly two singlets.  The correct way to handle this is with
configuration interaction since this would allow you to mix singlet and
triplet states.  You may well find that unrestricted HF will give you a
reasonable approximation while always in the singlet state.

Dr. Ross Underhill
Royal Military College of Canada
Kingston, Ontario
(613) 541-6000 X6175

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