From jomal:~at~:chopin.dfq.ufrj.br  Wed Oct  6 18:14:13 1993
Date: Wed, 6 Oct 1993 18:14:13 GMT
From: jomal*- at -*dfq.ufrj.br (Joao Otavio M.A. Lins )
Message-Id: <9310061814.AA15882 |-at-| dfq.ufrj.br>
To: chemistry%!at!%ccl.net, dave.gray%!at!%durham.ac.uk
Subject: Re: zwitterions w/ MOPAC



	Dear David.

	IHMO, the Hartree-Fock method is not suitable to calculate properties
of  zwitterions,  either  at ab-initio or semi-empirical levels.  You'll need
to perform some kind of multiconfigurational method,  like MCSCF or GVB.  The
correlation effects will be very important too and can not be neglect. And if
you plan to compare these properties with condensed phase data, you will need
to include the solvent effects either with the supermolecule (not desireable)
or SCRF approaches.
	As you can see, this is not an easy task.   (:

	Hope this helps,

				Joao O.M.A. Lins
			   Theoretical Chemistry Group
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