Subject: thanks for responses on Hund etc

From: Eric Scerri <[email-masked]>
Date: Wed, 15 Nov 2000 11:08:11 -0800

Thanks to all who responded to my request for whether or not Hund's 
rule of maximum spin multiplicity.

I think the variety of responses in itself says something about these 
kinds of questions,
namely that issues of this kind are rather unclear and it really 
depends on what one means by a theoretical justification/derivation.

I hope to collate responses and post them soon.

So far we have three types of responses which I characterize as,

(1)   weak plausibility explanations whereby unpaired electrons in 
different degenerate orbitals are justified on the basis of the Pauli 
type repulsion etc.

(2)   Somewhat stronger plausibility explanations based on the 
Hartree-Fock treatment of helium as found in several textbooks.  Too 
bad that that the ground state of the helium atom does not require us 
to invoke Hund's rule although it is obviously of some value to see 
that the triplet state is more stable that the singlet according to 
the formalism.   How about a general argument for any atom or is this 
asking for too much?

(3)   Stronger arguments yet which appeal to published articles which 
I have not yet had time to dig up.

I hope I am not being too negative in my broad assessment?

I also recall an interesting article by Jorgensen and Katriel of 
several years ago which I need to find.

regards,
eric scerri
-- 
Eric Scerri ,
Visiting Professor,
UCLA,
Department of Chemistry & Biochemistry,
607 Charles E. Young Drive East,
Los Angeles,  CA 90095-1569
USA

E-mail :   [email-masked]
tel:  310 206 7443
fax:  310 206 2061
Web Page:    http://www.chem.ucla.edu/dept/Faculty/scerri/index.html

Editor  of  Foundations of Chemistry
http://www.wkap.nl/journalhome.htm/1386-4238

Also see International Society for the Philosophy of Chemistry
http://www.georgetown.edu/earleyj/ISPC.html