Subject: Re: CCL:SUMMARY DFT ORBITALS, WF

From: "Alexandre Hocquet" <[email-masked]>
Date: Thu, 31 Aug 2000 18:19:57 GMT

>(2) The Fukui function (R. G. Parr and W. Yang, J Am Chem Soc, 1984,
>106, 4049) seems to be always discussed in the context of DFT; yet this
>function is "a chemical reactivity index in the sense of the
>frontier-electron theory of reactivity..." (R. G. Parr and W. Yang,
>"Density-Functional Theory of Atoms and Molecules", Oxford, New York,
>1989, p. 101). But in pure DFT theory there are no frontier orbitals.
>Isn't this strange?

Dear E. Lewars,

To add a late 2 francs contribution,
a clear distinction between "computational" dft and "conceptual" dft would 
help.
Computational dft is a tool used to compute quantum mechanics of chemical 
systems that has advantages and shortcomings, like questionnable virtual 
orbitals, etc...
Conceptual dft, whose bible is the book of Parr and Yang, is a genuine 
theory of molecular electronic structure as described by quantum mechanics. 
As has been pointed out, the concept of fukui functions may then be defined 
without explicitely referring to frontier orbitals.
Furthermore, concepts defined in conceptual dft may be computed by other 
tools like a HF calculation.
For example, if one approximates the chemical potential as the mean of Elumo 
and Ehomo, and feels the lumo is poorly described by a Kohn Sham orbital he 
may resort to HF orbitals.
Yours,

------------------------------------------------------------
Alexandre HOCQUET
Laboratoire de Physicochimie Biomoléculaire et Cellulaire
ESA CNRS 7033
[email-masked]
Fax: 0144277560
(do not dial first 0 from abroad)
LPBC, case courrier 138
4 Place Jussieu, 75252 PARIS Cedex 05 France
------------------------------------------------------------

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