Resonance states of atomic Di-anions

Metastable states of O (2-), S (2-), B (2-), and Al (2-) are studied in the framework of the complex absorbing potential method using highly correlated multireference configuration interaction wave functions. The first row species O (2-) and B (2-) are found to be broad resonances showing widths of roughly 1.7 eV, whereas the second row systems S (2-) and Al (2-) possess widths clearly smaller than 1 eV. The identified resonance states are compared to the fundamental H (2-) resonance, and the relationship with recent electron scattering experiments is discussed.