Spin--orbit ab initio curves of ⁸⁰Se₂⁺ ion and theassignment of photoelectron spectra of ⁸⁰Se₂ molecule

This paper carries out ab initio calculations to study the ⁸⁰Se₂(X³\Sigma_g^-) state and ⁸⁰Se₂⁺(X²\Pi_g, ⁸⁰Se₂⁺(a⁴\Pi_g) states by using completed active space self-consistent field and multi-reference second order perturbation theory. The electronic curves of these states including spin--orbit coupling are calculated, and then the spectroscopic parameters are obtained. The photoelectron spectra of ⁸⁰Se₂ molecule in gas phase are assigned according to Franck--Condon analysis based on calculated potential energy curves. The ionization energies of ⁸⁰Se₂ molecule are determined by the present calculation.