ELECTRONIC STRUCTURE OF DIOXIDE CfO2

The electronic structure of CfO2 is calculated in the fully relativistic cluster approximation of the discrete variation method (RDV). Theoretical X-ray photoelectron spectroscopy (XPS) spectrum of valence electrons is obtained in the range of electron binding energies 0 -…~40 eV. It is shown that outer valence molecular orbitals (OVMOs) in the energy range 0 -…~15 eV are formed by atomic orbitals Cf 5f and Cf 6p. The inner valence molecular orbitals (IVMOs) in the energy range ~15 -…~40 eV are formed mainly by Cf 6p3/2 and O 2s AOs. Significant covalent effects in CfO2 are due to the strong overlap of AOs with the ligand′s orbitals such as Cf 6d as well as Cf 5f and Cf 6p. The structure of MOs formed by Cf 6d, 7s, and 7p AOs differs only slightly from those of dioxides of lighter actinides. These MOs, together with those containing O 2s and O 2p AOs, form a “rigid framework” where MOs containing An 5f AOs move. We suggest a theoretical scheme of MOs that allows understanding the nature of chemical bonding and the structure of the XPS spectrum of valence electrons in CfO2.