Employing Range Separation on the meta-GGA Rung: New Functional Suitable for Both Covalent and Noncovalent Interactions

TL;DR

This paper introduces a new range-separated hybrid functional, LC-PBETPSS, that improves the accuracy of density functional theory calculations for covalent and noncovalent interactions by combining theoretical derivation and empirical optimization.

Contribution

It develops a novel scheme to convert existing exchange functionals into range-separated hybrids, specifically creating the LC-PBETPSS functional suitable for diverse chemical interactions.

Findings

Robust performance in noncovalent interaction energies

Accurate barrier heights and thermochemistry results

Effective excitation energy predictions

Abstract

We devise a scheme for converting an existing exchange functional into its range-separated hybrid variant. The underlying exchange hole of the Becke-Roussel type has the exact second-order expansion in the interelectron distance. The short-range part of the resulting range-separated exchange energy depends on the kinetic energy density and the Laplacian even if the base functional lacks the dependence on these variables. The most successful practical realization of the scheme, named LC-PBETPSS, combines the range-separated PBE exchange lifted to the hybrid meta-GGA rung and the TPSS correlation. The value of the range-separation parameter is estimated theoretically and confirmed by empirical optimization. The D3 dispersion correction is recommended for all energy computations employing the presented functional. Numerical tests show remarkably robust performance of the method for noncovalent interaction energies, barrier heights, main-group thermochemistry, and excitation energies.