Electronic structure, magnetic interactions, and the role of ligands in Mn_n(n=4,12) single-molecule magnets

We report our first principles calculation studies of electronic structure and magnetic properties of the Mn_n (n=4,12) single-molecule magnet, i.e., [Mn₄O₃Cl(OAc)₃(dbm)₃] (dbmH=dibenzoyl-methane) and [Mn₁₂O₁₂(CH₃COO)₁₆(H₂O)₄] molecules. For the calculations, we used the localized pseudoatomic orbital method based on the density functional theory within local density approximation. To investigate the role of ligand and its contribution to the determination of the magnetic properties, we calculated the electronic structures of Mn_n clusters with different ligand configurations. The detailed analysis reveals an important contribution of the bridging carbon atoms, connecting the Mn-O core and the outer ligand complex, to the magnetic ground states of the magnetic molecules. In addition, we calculated the effective exchange-coupling constants among Mn ions.