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Dispersion, static correlation, and delocalisation errors in density functional theory : an electrostatic theorem perspective.

Dwyer, A.D. and Tozer, D.J. (2011) 'Dispersion, static correlation, and delocalisation errors in density functional theory : an electrostatic theorem perspective.', Journal of chemical physics., 135 (16). p. 164110.

Abstract

Dispersion, static correlation, and delocalisation errors in density functional theory are considered from the unconventional perspective of the force on a nucleus in a stretched diatomic molecule. The electrostatic theorem of Feynman is used to relate errors in the forces to errors in the electron density distortions, which in turn are related to erroneous terms in the Kohn-Sham equations. For H2, the exact dispersion force arises from a subtle density distortion; the static correlation error leads to an overestimated force due to an exaggerated distortion. For H2+, the exact force arises from a delicate balance between attractive and repulsive components; the delocalisation error leads to an underestimated force due to an underestimated distortion. The net force in H2+ can become repulsive, giving the characteristic barrier in the potential energy curve. Increasing the fraction of long-range exact orbital exchange increases the distortion, reducing delocalisation error but increasing static correlation error.

Item Type:Article
Full text:PDF - Published Version (2428Kb)
Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1063/1.3653980
Publisher statement:© 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Dwyer, A.D. and Tozer, D.J. (2011) 'Dispersion, static correlation, and delocalisation errors in density functional theory : an electrostatic theorem perspective.', Journal of chemical physics., 135 (16). p. 164110 and may be found at http://dx.doi.org/10.1063/1.3653980
Record Created:25 Sep 2012 11:35
Last Modified:26 Sep 2012 10:05

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