Ab initio study of the electronic spectrum of a Cs₁₁O ₃ cluster

Geometries and electronic states of the cesium suboxide cluster Cs ₁₁O₃ are investigated by means of ab initio Hartree-Fock calculations. Relativistic effective core potentials are employed to represent core electrons in the atoms while Gaussian-type orbital basis sets are used to describe the valence electrons. Interatomic distances are optimized for the ground electronic state. The work function of Cs₁₁O₃ is calculated as 0.65 eV, in excellent agreement with an experimentally determined value of 0.7 eV for bulk cesium suboxide. Mulliken populations of negatively charged and neutral Cs₁₁O₃ clusters are calculated and indicate that upon ionization the emitted electron exits a molecular orbital encompassing the outermost cesium layer of the cluster.