A density-fitting implementation of the density-based basis-set correction method

TL;DR

This paper introduces an efficient implementation of the density-based basis-set correction method using density-fitting in MOLPRO, significantly improving basis convergence for MP2 reaction energies at lower computational cost.

Contribution

It presents a density-fitting implementation of the DBBSC method, enhancing basis-set convergence in wave-function calculations with a novel approach and benchmarking against MP2-F12.

Findings

DBBSC accelerates basis convergence of MP2 energies

The method reduces computational cost compared to MP2-F12

It improves reaction energy calculations without full F12 accuracy

Abstract

This work reports an efficient density-fitting implementation of the density-based basis-set correction (DBBSC) method in the MOLPRO software. This method consists in correcting the energy calculated by a wave-function method with a given basis set by an adapted basis-set correction density functional incorporating the short-range electron correlation effects missing in the basis set, resulting in an accelerated convergence to the complete-basis-set limit. Different basis-set correction density-functional approximations are explored and the complementary-auxiliary-basis-set single-excitation correction is added. The method is tested on a benchmark set of reaction energies at the second-order M{\o}ller-Plesset (MP2) level and a comparison with the explicitly correlated MP2-F12 method is provided. The results show that the DBBSC method greatly accelerates the basis convergence of MP2 reaction energies, without reaching the accuracy of the MP2-F12 method but with a lower computational cost.