Correlation energy from random phase approximations: A reduced density matrices perspective. Issue 1 (28th August 2017)

• Record Type: Journal Article
• Authors: Pernal, Katarzyna
• Other Names: Brändas Erkki guestEditor.; Hoffmann Mark R. guestEditor.
• Is Part Of: International journal of quantum chemistry. Volume 118:Issue 1(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-08-28
• Subjects: adiabatic connection formula -- electron correlation energy -- random phase approximation -- reduced density matrices; Quantum chemistry -- Periodicals; 541.28
• DOI: 10.1002/qua.25462
• Languages: English
• ISSNs: 0020-7608

Abstract

Abstract: Random phase approximation (RPA) electron correlation methods have gained in popularity in the recent years. A number of RPA correlation energy variants emerged in the Kohn–Sham DFT framework and in the theory of strongly orthogonal geminals. Foundations of most RPA approaches trace back to an exact expression for two‐electron reduced density matrix written in terms of one‐electron density matrix and dynamic one‐electron response functions, originally presented in the seminal paper of McLachlan and Ball ( Rev. Mod. Phys . 1964, 36, 844). The aim of this article is to give a pedagogical introduction to possible approaches for describing electron correlation energy based on the McLachlan and Ball formula. The focus of the presentation is to formulate electron‐interaction energy expressions as functions of reduced density matrices. On one hand, it provides a common umbrella for RPA approximations proposed for uncorrelated (Hartree–Fock or Kohn–Sham) as well as partially correlated (strongly orthogonal geminals) references. On the other hand, such presentation may stimulate new developments in density matrix functional theory. Abstract : Random phase approximation (RPA) methods for describing electron correlation are becoming a widely used tool in the arsenal of quantum chemistry methods. This tutorial article gives a pedagogical introduction to different variants of RPA approaches. The focus is on presenting correlation energy formulae as functions of reduced density matrices.