Comment on: Doubly hybrid density functional xDH-PBE0 from a parameter-free global hybrid model PBE0 (J. Chem. Phys. 136, 174103 (2012))

摘要

We have compared the performance of Grimme style DH/DSD and Zhang-Xu-Goddardtype xDH/xDSD forms for double hybrids. In the DH and DSD forms, KS orbitalswith elevated HF exchange and damped DFT correlation are used, while in the xDHand xDSD forms, the KS orbitals are obtained from a conventional hybridfunctional with undamped DFT correlation. Generally, the difference inperformance between DSD and xDSD functionals is small, slightly favoring xDSD.Augmentation of the xDH form with either same-spin MP2 correlation or adispersion correction markedly improves performance. Best xDSD results appearto be obtained for orbitals obtained with `exact exchange' fractions in the50-70% range. The orbitals for xDSD appear to be fairly transferable betweendifferent correlation functionals.