On the Role of Valence and Semi-Core Electron Correlation on Spin-Gaps in Fe(II)-Porphyrins

15 October 2018, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The role of valence and semi-core correlation in differentially stabilizing the intermediate spin-state of Fe(II)-porphyrins is analyzed. CASSCF treatment of the valence correlation, with a (32,34) active space containing metal 3d, 4d orbitals
and the entire π system of the porphyrin, is necessary to stabilize the intermediate spin-state for this system. Semi-core correlation provides a quantitatively significant (~1.5 kcal/mol) but less important correction. Accounting for both types of correlation enlarges the (3Eg5A1g) spin-gap to −5kcal/mol.


CASSCF wave functions
Stochastic simulation models
quantum Monte Carlo wave function
Active Space Dependence
coupled cluster theory
electron correlation treatment
valence correlation
core correlation correction
Electron Density Distributions
Wave Function Theory
Gouterman orbitals
Gouterman model
Natural Orbitals


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