Do Double Hybrid Functionals Benefit from Regularization in the PT2 term? Observations from an Extensive Benchmark

11 March 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


We put to the test a recent suggestion [Shee, J.; Loipersberger, M.; Rettig, A.; Lee, J.; Head-Gordon, M. J. Phys. Chem. Lett. 2021, 12 (50), 12084–12097] that MP2 regularization might improve the performance of double-hybrid density functionals. Using the very large and chemically diverse GMTKN55 benchmark, we find that κ-regularization is indeed beneficial at lower percentages of Hartree-Fock exchange, especially if spin-component scaling is not applied (such as in B2GP-PLYP or ωB97M(2)). This benefit dwindles for DSD and DOD functionals, and vanishes entirely in the ca. 70% HF exchange region optimal for them.


density functional theory
double hybrids
thermochemical kinetics

Supplementary materials

ESI for the main paper
See detailed inventory in the paper itself


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