Spin-unrestricted random-phase approximation with range separation: Benchmark on atomization energies and reaction barrier heights

TL;DR

This study evaluates various spin-unrestricted RPA methods with range separation for calculating atomization energies and reaction barriers, finding that the RPAx-SO2 variant offers the highest accuracy across these properties.

Contribution

The paper extends the RPAx-SO2 method to a spin-unrestricted formalism and benchmarks its performance, demonstrating its superior accuracy for thermochemical properties.

Findings

Range separation improves RPA accuracy significantly.

RPAx-SO2 provides the most accurate results among tested variants.

Validated RPAx-SO2 as a versatile tool for chemical property calculations.

Abstract

We consider several spin-unrestricted random-phase approximation (RPA) variants for calculating correlation energies, with and without range separation, and test them on datasets of atomization energies and reaction barrier heights. We show that range separation greatly improves the accuracy of all RPA variants for these properties. Moreover, we show that a RPA variant with exchange, hereafter referred to as RPAx-SO2, first proposed by Sz-abo and Ostlund [A. Szabo and N. S. Ostlund, J. Chem. Phys. 67, 4351 (1977)] in a spin-restricted closed-shell formalism, and extended here to a spin-unrestricted formalism , provides on average the most accurate range-separated RPA variant for atomization energies and reaction barrier heights. Since this range-separated RPAx-SO2 method had already been shown to be among the most accurate range-separated RPA variants for weak intermolecular interactions [J. Toulouse, W. Zhu, A. Savin, G. Jansen, and J. G. {\'A}ngy{\'a}n, J. Chem. Phys. 135, 084119 (2011)], this works confirms range-separated RPAx-SO2 as a promising method for general chemical applications.