Subject: (2) basis set balance continued

From: [email-masked] (Douglas A. Smith Ph.D.)
Date: Mon, 27 Jan 1997 15:25:01 -0500

OK, so the real issue is BSSE and basis set flexibility for describing the
space available to all electrons.  For the latter, would the use of CI or
multi-reference-CI help alleviate the problem?  Would that be a more
expensive cure than using a balanced basis?

What, then, happens when one is performing calculations on systems
containing both very heavy atoms and very light atoms, let's say, a
lanthanide and hydrogen?  If one uses an all electron basis for both atoms,
isn't the basis set unbalanced?  Is this at least part of the reason for
effective core potentials (ECPs) -- in addition to the problem of just
handling all the electrons in a reasonable time at reasonable cost?

Doug
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