Subject: Radical_HOMO/SOMO_problem

From: <[email-masked]>
Date: Mon, 24 Oct 1994 11:21:49 MET-DST

Dear netters,

I optimized the geometry of OH radical by applying 2 methods:
a) semiempirical AM1 method, UHF level of theory
b) ab initio, UMP2 and QCISD(T)/6-311+G(2d,p)
The problem is that the eigenvalue of the highest alpha spin orbital 
containing the unpaired electron is lower than the eigenvalue of the
highest beta spin orbital. According to the Koopmans' theorem, the
ionization potential is then given as the negative of the highest 
orbital, being beta spin orbital in this case. Does someone has the 
idea how to interpret these results?

	Zeljka Medven
	Rugjer Boskovic Institute
	Bijenicka 54, POB 1016
	HR-41001 Zagreb, CROATIA
	e-mail:[email-masked]
	fax:(385-41) 27 26 48
	phone:(385-41) 46 10 89