Tuesday, December 18, 2012

1212.3674 (Xinguo Ren et al.)

Renormalized Second-order Perturbation Theory for The Electron
Correlation Energy: Concept, Implementation, and Benchmarks

Xinguo Ren, Patrick Rinke, Gustavo E. Scuseria, Matthias Scheffler
We present a renormalized second-order perturbation theory (rPT2), based on an (approximate) Kohn-Sham (KS) reference state, for the electron correlation energy that combines the random-phase approximation (RPA), second-order screened exchange (SOSEX), and renormalized single excitations (rSE). These three terms all involve a summation of certain types of diagrams to infinite order, and can be viewed as "\textit{renormalizations}" of the 2nd-order direct, exchange, and single excitation (SE) terms of Rayleigh-Schr\"odinger perturbation theory based on an KS reference. In this work we establish the concept of rPT2 and present the numerical details of our SOSEX and rSE implementations. A preliminary version of rPT2, in which the renormalized SE (rSE) contribution was treated approximately, has already been benchmarked for molecular atomization energies and chemical reaction barrier heights and shows a well balanced performance [Paier \textit{et al}, New J. Phys. \textbf{14}, 043002 (2012)]. In this work, we present a refined version of rPT2, in which we evaluate the rSE series of diagrams rigorously. We then extend the benchmark studies to non-covalent interactions, including the rare-gas dimers, and the S22 and S66 test sets. We conclude that rPT2 gives an excellent overall performance across different chemical environments, and is a promising step towards a generally applicable electronic structure approach.
View original: http://arxiv.org/abs/1212.3674

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