Geometries and electronic structures of Ga2Se3, Ga3Se2 and their anions. Theoretical insights

We hereby report a theoretical study on the equilibrium geometries, electronic structures and harmonic vibrational frequencies of Ga2Se3, Ga3Se2 and their anions. The ground and low-lying excited states of Ga2Se (3) (-) , Ga2Se3, Ga3Se (2) (-) and Ga3Se2 are studied at the B3LYP and/or MP2 and CCSD(T) levels in conjunction with 6-311+G(d) and 6-311+G(2df) one particle basis sets. Ga2Se (2) (-) adopts the C-2v kite geometry while Ga2Se3 has a 'V' geometry. Ga3Se (2) (-) has a three-dimensional 'D-3h ' geometry and Ga3Se2 prefers the three-dimensional 'C-2v ' structure. Electron detachment energies from the ground electronic states of the anions to several neutral states are reported and discussed. At CCSD(T)//MP2 level, the adiabatic electron affinity (AEA) of Ga2Se3 is calculated to be 3.23 eV when using the 6-311+G(2df) basis set and that of Ga3Se2 is 2.77 eV with the 6-311+G(d) basis set. The findings of this research are analyzed and compared with gallium oxide and sulfide analogues.