Electronic Structure and Nature of Chemical Bonds in BkO2

The first calculations of the electronic structure and X-ray photoelectron spectrum (XPS) of valence electrons of BkO2 in the 0 to ~50 eV range of binding energies are made via relativistic discrete-variational method (RDV). Satisfactory agreement is established between the calculated and experimental spectra of this dioxide, obtained in the works of other authors. A quantitative molecular orbitals (MO) scheme is constructed that allows us to understand the nature of the chemical bonds and the structure of the XPS of valence electrons in BkO2. In contrast to the concepts of the crystal field theory, the effects of covalence in BkO2 are considerable and result in strong overlapping not only of the Bk6d, but of Bk6p, 5f atomic orbitals (AO) with ligand orbitals as well. It is found that the electrons of inner valence molecular orbitals (IVMO) weaken the chemical bonds caused by the electrons of outer valence molecular orbitals (OVMO) by 28%.