A New Family of Nonempirical Range-Separated Functionals: RSX-r2SCAN, RSX-r2SCAN0, and RSX-r2SCAN-QIDH

Abstract We extend the restored-regularized Strongly Constrained and Appropriately Normed (r2SCAN) nonempirical exchange-correlation functional to the Range-Separation eXchange (RSX) scheme, RSX-r2SCAN, where the range-separation parameter (ω) is obtained by applying a first-principles constraint, thus not relying on any empirical fitting. The corresponding exchange-correlation hybrid (i.e., RSX-r2SCAN0) and double-hybrid (i.e., RSX-r2SCAN-QIDH) versions are also built following this procedure, concomitantly assessing all the models on relevant systems (e.g., increasingly larger clusters of noninteracting He atoms) and a large data set of ionization potentials (e.g., GW100). The assessment is also done using the GMTKN55 database for general main-group thermochemistry, kinetics, and noncovalent interactions, along with the WTMAD-2 error metric and a more recent one called WTMAD-4. The assessment is completed with a detailed analysis of some of the GMTKN55 subsets most affected by self-interaction errors. Finally, the models are coupled to the VV10 correlation energy functional (RSX-r2SCAN-NL, r2SCAN0-NL, and RSX-r2SCAN-QIDH-NL) for nonlocal and long-range electronic effects, to accurately address noncovalently bound systems as well.