From:	young (- at -) slater.cem.msu.edu (Dave Young)
Date:	Mon, 21 Nov 94 13:38:50 -0500
Subject:	mulliken populations

Hello,

	There was a question about basis set dependence of the
mulliken population analysis.  Generally, the answer is that there
is a basis set dependence and it is often very large.

	The arbitrary 50-50 split of overlap populations makes some
sense for minimal basis sets and covalent compounds.  For ionic
compounds, 50-50 split should be suspect immediately.  With difuse
basis sets, the diffuse functions may be so far from the nucleus they
are centered on that they are describing the other nuclei more than
the one they are centered on.

	Somewhat better results are obtained with the Reid & Weinhold
natural orbital analysis.

	Probably the least basis set dependent results come from the
electrostatic analysis in which atomic charges are determined by
a least squares fit to the electrostatic potential.

	Hope this helps.

				Dave Young
				young()at()slater.cem.msu.edu
				youngdc[ AT ]msucem

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	Atkinson's First Law of Computing

Every last little thing about computers is very simple.
There are just an awful lot of them to remember.

					TVA (Tom V. Atkinson)

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