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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