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A hybrid functional is an exchange-correlation functional used in density functional theory (DFT) that incorporates a portion of exact exchange from Hartree-Fock theory with exchange and correlation from other sources (ab initio, such as LDA, or empirical).
Additional recommended knowledge
The hybrid approach to density functionals was first introduced by Axel Becke in 1993. Hybridization with Hartree-Fock (exact) exchange provides a simple scheme for improving many molecular properties, such as atomization energies, bond lengths and vibration frequencies, which tend to be poorly described with simple ab initio functionals.
The exchange-correlation functional for a hybrid is usually a linear combination of the Hartree-Fock exchange () and some other one or combination of exchange and correlation functionals. The parameter(s) relating the amount of each functional can be arbitrarily assigned and is usually fitted to reproduce well some set of observables (bond lengths, band gaps, etc.). For example, the popular B3LYP (Becke, three-parameter, Lee-Yang-Parr) exchange-correlation functional is:
List of hybrid functionals (in Gaussian 03)
See: G03 Manual: DFT.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hybrid_functional". A list of authors is available in Wikipedia.|