SCAN-based hybrid and double-hybrid density functionals from models without fitted parameters

TL;DR

This paper introduces new hybrid and double-hybrid density functionals based on the nonempirical SCAN functional, achieving improved accuracy across various chemical applications without using fitted parameters.

Contribution

It develops SCAN-based hybrid and double-hybrid functionals that are parameter-free and outperform their parent functionals in key chemical problems.

Findings

SCAN0-2 achieves high accuracy in thermochemistry and kinetics.

The new functionals effectively address self-interaction and noncovalent interactions.

They outperform original SCAN in diverse applications.

Abstract

By incorporating the nonempirical SCAN semilocal density functional [Sun, Ruzsinszky, and Perdew, Phys. Rev. Lett. 115, 036402 (2015)] in the underlying expression of four existing hybrid and double-hybrid models, we propose one hybrid (SCAN0) and three double-hybrid (SCAN0-DH, SCAN-QIDH, and SCAN0-2) density functionals, which are free from any fitted parameters. The SCAN-based double-hybrid functionals consistently outperform their parent SCAN semilocal functional for self-interaction problems and noncovalent interactions. In particular, SCAN0-2, which includes about 79% of Hartree-Fock exchange and 50% of second-order Moller-Plesset correlation, is shown to be reliably accurate for a very diverse range of applications, such as thermochemistry, kinetics, noncovalent interactions, and self-interaction problems.