Theoretical studies of electronic excited states for [Formula Presented]

A theoretical investigation of the electronic excited states of [Formula Presented] is presented by employing the multiple-scattering model. All the excited states are treated in a unified manner in the framework of quantum defect theory. For the relatively low excited states, our calculated transition energies are in good agreement with the experimental data and could help to assign the spectra bands. For the high excited states, we present the quantum defects for all Rydberg series, which call for further experimental verifications.