

You could do a 10 orbital CASSCF and then add on the
second order perturbation corrections.  DOing a 20 orbital CASSCF
will probably not be that great anyway because you do not include
the dynamical correlation.  I would bet that the smaller CAS + PT2
will work better.  I doubt you can do better than 1/2 eV in accuracy
with such a calculation and your small basis sets.

	What is the system you are trying to compute?  

	Best Regards

	Chuck Martin
	W.M. Keck Center for Molecular Electronics
	Syracuse University

	[email-masked]
	
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