Ab initio correlation approach to a ferric wheel-like molecular cluster

TL;DR

This paper investigates electronic correlation effects in a ferric wheel-like molecular cluster using ab initio methods, revealing the influence of ligand groups on magnetic exchange parameters and confirming experimental values.

Contribution

It introduces a comprehensive ab initio approach combining multiple computational methods to study correlation effects in a ferric cluster, highlighting ligand influence on magnetic properties.

Findings

The bridge oxygen atoms have a lesser impact on the exchange parameter than apical ligands.

The computational results agree with experimental exchange parameter values.

Electronic correlation effects significantly influence magnetic interactions in the cluster.

Abstract

We present an ab initio study of electronic correlation effects in a molecular cluster derived from the hexanuclear ferric wheel [LiFe6(OCH3)12-(dbm)6]PF6. The electronic and magnetic properties of this cluster have been studied with all-electron Hartree-Fock, full-potential density functional calculations and multi-reference second-order perturbation theory. For different levels of correlation, a detailed study of the impact of the electronic correlation on the exchange parameter was feasible. As the main result, we found that the influence of the bridge oxygen atoms on the exchange parameter is less intense than the influence of the apical ligand groups, which is due to the geometry of the cluster. With respect to the cluster model approach, the experimental value of the exchange parameter was affirmed.