Density functional theory is the most widely used electronic structure method, due to its simplicity and cost-effectiveness. The accuracy of DFT depends not only on the choice of Kohn-Sham functional but also on the density produced by it. SCAN is a modern functional that satisfies all known constraints for meta-GGA functionals. The density-driven errors, defined as the error introduced by a DFT density compared to the true one, often limit the accuracy of SCAN.<br/> <br/>Density-corrected DFT (DC-DFT) can alleviate this shortcoming by using a better density which, in most cases, is the density obtained at the Hartree-Fock level for efficiency purposes. In this work, we present extensive calculations aimed at determining the accuracy of the DC-SCAN functional for water and hydrated ions, which show remarkable consistency in reproducing reference results obtained at the coupled cluster, CCSD(T), level, with minimal loss of accuracy. Besides aqueous systems, we analyze the performance of DC-SCAN for the diverse GMTKN55 dataset, which includes 55 different subsets involving thermochemistry, barrier-heights, inter-, and intra-molecular non-covalent interactions, and reaction energies. To this end, we introduce an rVV10 dispersion correction specifically parametrized for DC-SCAN to accurately describe long-range interactions. We show that the DC-SCAN-rVV10 functional provides more accurate results than DC-SCAN for the overall dataset, especially for barrier-heights and non-covalent interactions, for which the density-driven errors are significant. Through a detailed density-sensitivity analysis, we demonstrate that DC-SCAN and DC-SCAN-rVV10 effectively achieve the same accuracy as expensive correlated wavefunction methods, but at the same cost as meta-GGA functionals.

How good is the density-corrected SCAN functional?

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.