Assessment of correlation energies based on the random-phase approximation

TL;DR

This paper systematically evaluates the performance of RPA-based methods and their extensions for calculating correlation energies, dissociation, and activation energies, demonstrating improved accuracy and balanced performance across various chemical systems.

Contribution

It provides a comprehensive benchmark of RPA and beyond-RPA methods, including SOSEX and SE corrections, highlighting their impact on energy calculations and reaction energetics.

Findings

RPA+SOSEX+rSE yields balanced accuracy for diverse energies.

Single excitation corrections improve binding energy predictions.

Activation energies are accurately predicted using RPA-based methods.

Abstract

The random-phase approximation to the ground state correlation energy (RPA) in combination with exact exchange (EX) has brought Kohn-Sham (KS) density functional theory one step closer towards a universal, "general purpose first principles method". In an effort to systematically assess the influence of several correlation energy contributions beyond RPA, this work presents dissociation energies of small molecules and solids, activation energies for hydrogen transfer and non-hydrogen transfer reactions, as well as reaction energies for a number of common test sets. We benchmark EX+RPA and several flavors of energy functionals going beyond it: second-order screened exchange (SOSEX), single excitation (SE) corrections, renormalized single excitation (rSE) corrections, as well as their combinations. Both the single excitation correction as well as the SOSEX contribution to the correlation energy significantly improve upon the notorious tendency of EX+RPA to underbind. Surprisingly, activation energies obtained using EX+RPA based on a KS reference alone are remarkably accurate. RPA+SOSEX+rSE provides an equal level of accuracy for reaction as well as activation energies and overall gives the most balanced performance, which makes it applicable to a wide range of systems and chemical reactions.