Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 2: Focussed session: Theory and computation of electronic structure: new frontiers I (jointly with HL, DS)

O 2.1: Topical Talk

Monday, March 14, 2011, 11:15–11:45, TRE Phy

Range separation: success, doubts and perspectives — •Andreas Savin — CNRS and UPMC Univ Paris 6, Laboratoire de Chimie Theorique, F-75252 Paris, France

The difficulty of finding simple approximations for density functionals can be alleviated by passing some of the exchange and correlation description to a wave function. A way to produce such hybrids is to consider that for short-range inter-electronic separations exchange and correlation effects are transferable and thus able to be captured by simple models.

Range-separated hybrids can be applied to different levels of density functional approximation (LDA, GGA, ...) and wave function approximation (single determinant, second order perturbation theory, RPA, coupled cluster, ...).

The methods do not bring significant improvement in most fields of application where density functional approximations have been successful. However, they improve accuracy when usual approximations fail, such as van der Waals interactions [1], or where self-interaction becomes an important issue. The computational effort is smaller than for the corresponding wave function method, mainly because smaller basis sets can be used.

Finally, some unexplored path / open questions will be discussed, such as the choice of the interaction operator, improving the density functional approximation, or the role of mixed "short-range/long-range terms".

[1] W. Zhu, et al, J. Chem. Phys., 132, 244108 (2010).