On the electronic structure of AlS₂ and AlS₂⁻

Abstract

The ground and low-lying excited states of AlS2and AlS−2have been studied using den-sity functional theory (DFT) and coupled cluster [CCSD(T)] approximations, in conjunc-tions with the 6-311+G(2df) one particle basis set. AlS2is linear with a2∏gground state.CCSD(T) predicts that the2A2state of the C2visomer is separated from the ground stateby less than 0.1 eV, while the2∏uand2∑+ustates in D∞hsymmetry are located at 0.67 eVand 1.40 eV, respectively, above the2∏gstate. The AlS−2anion possesses a1∑+ggroundstate with a very similar geometry with the neutral molecule. At the CCSD(T) level, adi-abatic electron detachment energies for the [AlS2(2∏g)←AlS−2(1∑+g)] transition is 4.03eV.