Exploring Avenues Beyond Revised DSD Functionals: II. Random-Phase Approximation and scaled MP3 corrections

TL;DR

This paper investigates replacing the problematic second-order perturbation component in revDSD double hybrids with the direct RPA, combined with dispersion and correlation corrections, leading to improved accuracy in diverse chemical systems.

Contribution

It introduces the use of dRPA as a replacement for the second-order perturbation in revDSD double hybrids and explores MP3-like corrections, enhancing performance on benchmark datasets.

Findings

dRPA-based double hybrids approach the performance of established methods.

Adding MP3-like corrections reduces WTMAD2 on the GMTKN55 benchmark.

The new methods show insensitivity to the choice of semilocal functional.

Abstract

For revDSD double hybrids, the G\"orling-Levy second-order perturbation theory component is an Achilles' Heel when applied to systems with significant near-degeneracy ("static") correlation. We have explored its replacement by the direct random phase approximation (dRPA), inspired by the SCS-dRPA75 functional of K\'allay and coworkers. The addition to the final energy of both a D4 empirical dispersion correction, and of a semilocal correlation component lead, to significant improvements, with DSD-PBEdRPA75-D4 approaching the performance of revDSD-PBEP86-D4 and the Berkeley $\omega$B97M(2). This form appears to be fairly insensitive to the choice of semilocal functional, but does exhibit stronger basis set sensitivity than the PT2-based double hybrids (due to much larger prefactors for the nonlocal correlation). As an alternative, we explored adding an MP3-like correction term (in a medium-sized basis sets) to a range-separated $\omega$DSD-PBEP86-D4 double hybrid, and found it to have significantly lower WTMAD2 (weighted mean absolute deviation) for the large and chemically diverse GMTKN55 benchmark suite; the added computational cost can be mitigated through density fitting techniques.