Towards a greater accuracy in DFT calculations From GGA to hybrid functionals
Résumé
The accuracy of a DFT calculation depends in a crucial way on the choice of the exchange-correlation functional, for which a variety of approximations are available. Local functionals, or functionals belonging to the generalized-gradient approximation (GGA) or meta-GGA classes are the simplest ones and the most computationally efficient. Furthermore, they give sufficiently accurate results for many applications. Nevertheless, for a number of purposes, an increased accuracy is required, which can only be obtained by means of hybrid functionals. Hybrid functionals are derived by mixing a GGA (or local, or meta-GGA) functional with the Hartree-Fock exchange. Two different families of hybrid functionals exist the so-called global hybrids and the range separated hybrids. Quite recently, hybrids combining the main features of the functionals belonging to both families have been proposed and tested. We have constructed new hybrid functionals based on some recently proposed local and GGA functionals. Global hybrids, range-separated hybrids, as well as global hybrids with range separation will be presented and their performances discussed. © Springer Science+Business Media Dordrecht 2012.