Subject: Harris functional

From: [email-masked] (Frederic BOUYER)
Date: Thu, 7 Sep 1995 11:47:31 +0100

Hi everybody,

I was wondering what is the Harris functional, in the DFT context, and what
are the main differences with the functionals used in programs (DGauss,
deMon, DMol, ADF, ...). Any comments would be appreciated and/or a summary.

Thank you in advance.

Frederic Bouyer

____________________________________________________________________
Frederic BOUYER
Laboratoire d'Electrochimie et de Chimie Analytique
Equipe "Reactivite en Milieux Ioniques Liquides" (G. PICARD)
ENSCP
11, rue Pierre et Marie Curie
75231 PARIS Cedex 05
FRANCE
Tel : (33)-1-43-54-53-84 ou (33)-1-44-27-67-51 ou (33)-1-44-27-66-94
Fax : (33)-1-44-27-67-50
E-mail : [email-masked]
http://alcyone.enscp.jussieu.fr/  created, in progress ...
http://alcyone.enscp.jussieu.fr/Pages/LECA/GP/FB/

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From: [email-masked] (Alain Kessi)
Date: Thu, 7 Sep 1995 15:47:45 +0200

> deMon, DMol, ADF, ...). Any comments would be appreciated and/or a summary.

The Harris functional is an alternative formulation to the Kohn-Sham
total energy functional. It is therefore not an alternative to the
exchange and correlation functionals such as the Perdew and Wang functional,
but uses such parametrizations as parts of its total energy expression
(just like the Kohn-Sham total energy formulation does).

As explained in the DSolid manual, the Harris functional is stationary at
the same density as the Kohn-Sham total energy functional and can therefore
be used instead for the SCF calculation. It has two advantages as compared
to the Kohn-Sham scheme. First, the density does not need to be
V-representable. Second, the curvature of the Harris functional about
the stationary point is smaller than the curvature of the Kohn-Sham
functional, so convergence is faster. Actually, the Harris functional was
originally developed for single-shot calculations rather than SCF convergence,
and for many purposes, the accuracy after the first iteration may be
sufficient.

DMol (and its periodic boundary conditions implementation DSolid) uses
the Harris functional.

--
Alain Kessi ([email-masked])
Paul Scherrer Institut, Zuerich, Switzerland