Title

Improved Spin-State Energy Differences of Fe(II) Molecular and Crystalline Complexes via the Hubbard U-corrected Density

Document Type

Article

Publication Date

4-28-2021

Disciplines

Inorganic Chemistry | Physical Chemistry

Abstract

We recently showed that the DFT+U approach with a linear-response U yields adiabatic energy differences biased toward high spin [Mariano et al. J. Chem. Theory Comput. 2020, 16, 6755–6762]. Such bias is removed here by employing a density-corrected DFT approach where the PBE functional is evaluated on the Hubbard U-corrected density. The adiabatic energy differences of six Fe(II) molecular complexes computed using this approach, named PBE[U] here, are in excellent agreement with coupled cluster-corrected CASPT2 values for both weak- and strong-field ligands resulting in a mean absolute error (MAE) of 0.44 eV, smaller than that of the recently proposed Hartree–Fock density-corrected DFT (1.22 eV) and any other tested functional, including the best performer TPSSh (0.49 eV). We take advantage of the computational efficiency of this approach and compute the adiabatic energy differences of five molecular crystals using PBE[U] with periodic boundary conditions. The results show, again, an excellent agreement (MAE = 0.07 eV) with experimentally extracted values and a superior performance compared with the best performers M06-L (MAE = 0.08 eV) and TPSSh (MAE = 0.31 eV) computed on molecular fragments.

Publication Title

Journal of Chemical Theory and Computation

Volume

17

Issue

5

First Page

2807

Last Page

2816

DOI

10.1021/acs.jctc.1c00034

Comments

The work performed at the University of South Dakota (USD) was supported by the Department of Energy, Basic Energy Sciences (DE-SC0019463). The computations performed at USD were performed on High Performance Computing, funded by NSF Award OAC-1626516.

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