Original scientific paper

Many-Body Perturbation Theory Based on Localized Orbitals

Ede Kapuy ; Department of Theoretical Physics, Jozsef Attilla University, H-6720 Szeged, Aradi vertanuk tere 1, Hungary
Zoltan Csepes ; Quantum Theory Group, Physics Institute, Technical University Budapest, H - 1521 Budapest, Budafoki ut 8, Hungary
Cornelia Kozmutza ; Quantum Theory Group, Physics Institute, Technical University Budapest, H - 1521 Budapest, Budafoki ut 8, Hungary

Abstract

Diagrammatic formulmion of the MBPT has been extended
to the case when both the occupied orbita'ls and the virtual ones
are separately localized, i.e., they are unitary transforms of the ·
canonical HF orbitals. All diagrams representing ground state
correlation energy are generated through the fifth order. For cyclic
polyenes C4n+z H4n+z as model systems, in PPP approximation, all
perturbation energy corrections through the fourth order have been
calculated for a wide range of the coupling constant: (J-1. Some
fifth order energy corrections have also been evaluated and the
convergence of the localization corrections has been studied. For
CsHs the results of the canonical and the localized versions have
been compared with those obtained by full CI. We have shown
that in the localized representation the energy corrections can be
partitioned into local and nonlocal contributions.

Keywords

Hrčak ID:

194059

URI

https://hrcak.srce.hr/194059

Publication date:

14.1.1985.

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