ELECTRONIC STRUCTURE AND CHEMICAL BONDING IN EsO2

The density of states of valence electrons of the EsO2 dioxide is calculated by the relativistic discrete variational method. The scheme of valence molecular orbitals (MOs) is constructed taking into account the photoelectric effect cross sections of valence electrons. The histogram of X-ray photoelectron spectra (XPS) is built for the electron binding energies from 0 eV to similar to 40 eV. It is shown that the structure of this spectrum contains contributions of outer valence orbitals (OVMOs, from 0 eV to similar to 15 eV) and inner valence orbitals (IVMOs, from similar to 15 eV to similar to 50 eV) molecular orbitals. It is established that Es 5f and Es 6p electrons participate in the chemical bonding. It is established that not only Es 6d, but also Es 6p and Es 5f orbitals overlap significantly with ligand orbitals, resulting in a highly covalent chemical bonding in this dioxide. The nature of chemical bonding and the structure of the XPS spectrum of valence electrons in EsO2 is clarified using the scheme of MOs. It is shown that the chemical bonding formed by OVMO electrons is weaken by one third due to IVMO electrons.