From owner-chemistry@ccl.net Wed Dec  9 02:45:01 2009
From: "Mikael Johansson mikael.johansson]=[helsinki.fi" <owner-chemistry _ server.ccl.net>
To: CCL
Subject: CCL: What's the reasonable range for Mulliken charges on metallic cluster?
Message-Id: <-40888-091209024304-23577-WDDRBac+2owD1JKRRtyKCw _ server.ccl.net>
X-Original-From: Mikael Johansson <mikael.johansson__helsinki.fi>
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Date: Wed, 9 Dec 2009 09:42:50 +0200 (EET)
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Sent to CCL by: Mikael Johansson [mikael.johansson%helsinki.fi]

Hello Tsung-Wen!

On Tue, 8 Dec 2009, Tsung-Wen Yen peter308:-:gmail.com wrote:

> My caluculation of Mulliken partial charge on noble metallic 
> clusters(N=38) has some peculiar results. Some of the atoms will show 
> 5~6 electrons. Is this reasonable? I used (RECP19|SD) basis set for Gold 
> and Copper. Could you tell me on which range should be reasonable for 
> MPA charges? I have the feeling my electron structure may have converged 
> to a wrong state. I appreciated for your advice.

Mulliken charges for metal systems can give you almost any random numbers. 
You should not use them for analysing anything important. Thus, a charge 
of 5-6 is not an indication of problems in your calculations, only in the 
way Mulliken charges are defined.

The most hilarious failure I've encountered is a charge of -78 on tungsten 
in WAu12:
   PCCP 6 (2004) 11-22, http://xlink.rsc.org/?DOI=B310395A

Have a nice day,
     Mikael J.
     http://www.iki.fi/~mpjohans/