Ab Initio Calculations for Spin-Gaps of Non-Heme Iron Complexes

• DOI: 10.1021/acs.jctc.9b00370
• Publication Date: 2019-07-02T19:59:01Z
• Authors: Quan Manh Phung; Carlos Martín-Fer...; Jeremy N. Harvey; Milica Feldt
• Keywords: Coupled cluster; Benchmark (surveying); Spin states

We employed our recently proposed multireference approach CASPT2/CC to calculate the quintet-triplet gaps ΔETQ of a series non-heme FeIV═O species and subsequently used these results benchmark density functional theory (DFT) as well two variants local coupled-cluster approaches (DLPNO-CCSD(T) LUCCSD(T0)). showed that current implementations method are not sufficiently accurate. DLPNO-CCSD(T) systematically overstabilizes quintet state, whereas LUCCSD(T0) overestimates triplet one. This sort systematic bias may be helpful in improving correlation methods can also basis for simple correction scheme.