Subject: Question to think about during a break

From: YONG HUANG <[email-masked]>
Date: Fri, 9 May 1997 11:08:10 -0500 (CDT)

Here's a simple question. Is a NaCl molecule (yes, molecule, maybe in gas phase 
or in a computational chemist's space) a radical? How's the spin density
distribution look like if it is? This has nothing to do with my research. Just 
a question.

Yong

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From: Charles Martin <[email-masked]>
Date: Fri, 9 May 1997 14:09:33 -0700

> distribution look like if it is? This has nothing to do with my research. Just 

	Similar question has been addressed by Steve Berry at the 
University of Chicago a long time ago (at least on some Halide
molecules).  The ground state changes character from covalent to 
ionic as the bond is stretched (i.e the typical problem addressed in
Landau-Zener hopping).    This is a very difficult problem 
with traditional ab initio methods because most ab initio methods 
can not treat curve crossings like this properly.  

	Chuck Martin

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 ||     Charles H. Martin                            ||
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 ||     Department of Chemistry                      ||
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