Approaching the basis-set limit of the dRPA correlation energy with explicitly correlated and Projector Augmented-wave methods

TL;DR

This paper compares plane wave and Gaussian basis set methods for dRPA calculations, achieving near basis-set limit accuracy for atomization energies using PAW and F12 approaches, with results agreeing within chemical accuracy.

Contribution

It demonstrates the convergence of dRPA atomization energies using PAW and F12 methods, providing detailed procedures for high-accuracy calculations in VASP and TURBOMOLE.

Findings

Agreement within 1 kcal/mol for all molecules

Root mean-square deviation of 0.41 kcal/mol for exchange energies

Root mean-square deviation of 0.33 kcal/mol for exchange plus RPA

Abstract

The direct random-phase approximation (dRPA) is used to calculate and compare atomization energies for the HEAT set and 10 selected molecules of the G2-1 set using both plane waves and Gaussian-type orbitals. We describe detailed procedures to obtain highly accurate and well converged results for the projector augmented-wave (PAW) method as implemented in the Vienna Ab-initio Simulation Package (VASP) as well as the explicitly correlated dRPA-F12 method as implemented in the TURBOMOLE package. The two approaches agree within chemical accuracy (1 kcal/mol) for the atomization energies of all considered molecules, both for the exact exchange as well as for the dRPA. The root mean-square deviation is 0.41 kcal/mol for the exact exchange (evaluated using density functional theory orbitals) and 0.33 kcal/mol for exact exchange plus the random-phase approximation.