Electron correlation effects in band structure of magnetic clusters Mn-12 and Fe-8

Abstract

We present calculations of electronic structure and local magnetic moment of 3d metals in [Mn12O12(CH3COO)(16)(H2O)(24)].2CH(3)COOH.4H(2)O and I(C6H15N3)(6)Fe8O2(OH)(12)]Br-7(H2O)Br.8H2O, abbreviated Mn-12 and Fe8Br8, respectively. The comparison of calculated and experimental soft X-ray spectra shows that p-d mixing is very sensitive to the value of the local Coulomb repulsion parameter U. This result is found to be in agreement with experimental resonant inelastic X-ray scattering spectra (RIXS) and X-ray photoelectron spectra (XPS), which have been used to study electron correlation effects in magnetic clusters. The O 2p-Me 3d separation found in the experiment, is well reproduced by LDA U band structure calculations, which include on-site Coulomb interactions. The 3d metal L-2,L-3 RIXS behaviour reflects the presence of the local magnetic moment and confirms the existence of the energy gap in the 3d band of the metal. (C) 2004 Elsevier B.V. All rights reserved.