Electron correlation effects in cobalt fluorides CoFn

The molecular cobalt fluorides CoF₂, CoF₃ and CoF₄ are studied and compared by employing different basis sets as well as Quantum Information Theory (QIT) to investigate their correlation effects. These prototypical monomers may be systematically extended in size yielding a novel quasi 1-dimensional, strongly correlated model system consisting of cobalt atoms bridged by oxygen atoms and fluorine termination on both ends. Accurate correlation energies are obtained using Full Configuration Interaction (FCI) and Full Configuration Interaction Quantum Monte Carlo (FCIQMC) calculations and the results are compared to Coupled Cluster and Density Matrix Renormalization Group (DMRG) energies. The analysis indicates the cobalt atom requires a larger number of one-electron basis functions than fluorine and the use of localized molecular orbitals may facilitate calculations for the extended systems.