Subject: Ground State with Correlation

From: "JDA03546@niftyse" <[email-masked]>
Date: Mon, 05 Jun 1995 08:26:00 +0900

Dear netters,

There is one thing which is bugging me.

There are two ( or more ) electronic states which have the same symmetric/spin
states. UHF says state 1 is the lowest energy while MP2 says state 2 is.
(It happenes quite often when I calculate some transition metal compounds.)

The simple interpretation is, state 2 is the real ground state taking into 
account
the electron correlation. But on the second thought, perturbation methods like
 
MP2
can be used only to the ground state. So the MP2 calculation on state 2 is 
meaningless?

How should I see this? And how can I find the "real ground state" accounting 
for the
electron correlation? Do I have to go to MCSCF?

Thanks in advance.

Kazuo