Ab initio and B3LYP–DFT calculations of GaP− and GaP2−: the electron affinities and vibrational frequencies of GaP and GaP2

CCSD(T) and B3LYP equilibrium geometries, harmonic vibrational frequencies and electron detachment energies are reported for GaP− and GaP2−. GaP− has a 2Σ+ ground state with a 2Π state 2.30 kcal/mol above, while GaP has a 3Σ− ground state and a 3Π state at 2.10 kcal/mol. The calculated adiabatic electron affinity (AEA) of GaP is 1.94 eV. GaP2− has a 1A1 ground state. The B3LYP and CCSD(T) AEA of GaP2(2B2) are 1.73 and 1.80 eV, respectively. The calculated spacings between the low-lying states and vibrational frequencies of GaP2− and GaP2 are compared with recent experimental anion photoelectron data.