Regularized and Opposite spin-scaled functionals from M{\o}ller-Plesset adiabatic connection -- higher accuracy at lower cost

TL;DR

This paper introduces a novel correlation energy method combining MP2 regularization and spin-scaling along the Møller-Plesset adiabatic connection, achieving higher accuracy for non-covalent interactions at lower computational cost.

Contribution

It develops the $c_{os}\kappa_{os}$-SPL2 method, which improves non-covalent interaction predictions by integrating interpolation, regularization, and spin-scaling strategies, outperforming existing approaches.

Findings

$c_{os}\kappa_{os}$-SPL2 surpasses individual strategies in accuracy.

Method is competitive with dispersion-corrected double hybrids.

Particularly effective for anionic halogen-bonded complexes.

Abstract

Non-covalent interactions (NCIs) play a crucial role in biology, chemistry, material science, and everything in between. To improve pure quantum-chemical simulations of NCIs, we propose a methodology for constructing approximate correlation energies by combining an interpolation along the M{\o}ller adiabatic connection (MP AC) with a regularization and spin-scaling strategy applied to MP2 correlation energies. This combination yields $c_{\rm os}\kappa_{\rm os}$-SPL2, which exhibits superior accuracy for NCIs compared to any of the individual strategies. With the $N^4$ formal scaling, $c_{\rm os}\kappa_{\rm os}$-SPL2, is competitive or often outperforms more expensive dispersion-corrected double hybrids for NCIs.The accuracy of $c_{\rm os}\kappa_{\rm os}$-SPL2 particularly shines for anionic halogen bonded complexes, where it surpasses standard dispersion-corrected DFT by a factor of 3 to 5.