DFT Estimation of Exchange Coupling Constant of Cr8 Molecular Ring using the Hybrid Functional B3LYP

A study of electronic and magnetic properties of an octametallic chromium-based homonuclear molecule Cr8F8(CO2 −C(CH3)3)16 is presented, using density functional theory (DFT) approach and linearized augmented plane wave (LAPW) method with Perdew, Burke and Ernzerhof (PBE) and Becke 3-term correlation (B3LYP) functionals. The exchange coupling parameters between transition metals ions are extracted, taking into account two di erent (ferroand antiferromagnetic) spin con gurations. The value J = 3.1 meV found for the hybrid B3LYP functional improves signi cantly the one obtained for the PBE functional and gives an evidence for the superiority of the former in simulation of molecular nanomgnets. Moreover, the hybrid functional yields excellent spin density localisation, an enhancement of the HOMO-LUMO gaps and the value 2.81μB of magnetic moment at the chromium centre in good agreement with experiment.