Correlated electron behavior of metalorganic molecules: insights from density functional theory combined with many-body effects using exact diagonalization

TL;DR

This paper combines density functional theory with exact diagonalization to analyze the electronic structure of metalorganic molecules, highlighting the importance of dynamical correlations and proposing a method to understand spin crossover phenomena.

Contribution

It introduces a combined DFT and many-body approach to accurately describe the electronic states of metalorganic molecules, especially for correlated systems like FeP.

Findings

Dynamical correlation effects are crucial for FeP's electronic structure.

FeP can potentially undergo spin crossover due to subtle energy balances.

The approach is applicable to a broad class of correlated organometallic molecules.

Abstract

A proper theoretical description of electronic structure of the 3d orbitals in the metal centers of functional metalorganics is a challenging problem. In this letter, we apply density functional theory and an exact diagonalization method in a many body approach to study the ground state electronic configuration of an iron porphyrin (FeP) molecule. Our study reveals that dynamical correlation effects are important, and FeP is a potential candidate for realizing a spin crossover due to a subtle balance of crystal field effects, on-site Coulomb repulsion and hybridization between the Fe d-orbitals and ligand N p-states. The mechanism of switching between two close lying electronic configurations of Fe-d orbitals is shown. We discuss the generality of the suggested approach and the possibility to properly describe the electronic structure and related low energy physics of the whole class of correlated metal centered organometallic molecules.