Accuracy of basis-set extrapolation schemes for DFT-RPA correlation energies in molecular calculations

TL;DR

This paper evaluates the accuracy of basis-set extrapolation schemes for RPA correlation energies in molecular DFT calculations, establishing benchmarks and comparing different extrapolation methods for improved energy predictions.

Contribution

It provides a benchmark set for RPA correlation energies and assesses the performance of various extrapolation schemes, including semiempirical methods, for molecular calculations.

Findings

Two-point extrapolation schemes with larger basis sets yield highly accurate energies.

Semiempirical extrapolation methods can also produce results close to benchmarks.

Different schemes vary in accuracy for atomization energy calculations.

Abstract

We construct a reference benchmark set for atomic and molecular random-phase-approximation (RPA) correlation energies in a density functional theory (DFT) framework at the complete basis set limit. This set is used to evaluate the accuracy of some popular extrapolation schemes for RPA all-electron molecular calculations. The results indicate that for absolute energies accurate results, clearly outperforming raw data, are achievable with two-point extrapolation schemes based on quintuple- and sextuple-zeta basis sets. Moreover, we show that results in good agreement with the benchmark can also be also obtained by using a semiempirical extrapolation procedure based on quadruple- and quintuple-zeta basis sets. Finally, we analyze the performance of different extrapolation schemes for atomization energies.