Density functional theory studies on the structure, electronic state and photoelectron spectroscopy of (GaP) n− ( n = 7–9) clusters

Abstract

The equilibrium geometries, electronic states, vibrational frequencies and energies of (GaP) n and (GaP) n − ( n = 7–9) have been calculated by hybrid B3LYP and B3PW91 functionals at 6-31+G(d) level. The results reveal that the lowest lying electronic states’ geometries of the neutral have the same molecular symmetry as the corresponding anions’. (GaP) 7 is shown to have a singlet ground state ( 1A 1) with C 3v symmetry. (GaP) 8 is found to be a closed-shell molecule with S 4 symmetry. (GaP) 9 takes on a singlet ground state ( 1A′) with C 3v symmetry. The charge-induced structural changes in these clusters have been discussed. Moreover, natural bond orbital (NBO) analysis implemented to gain insight into the bonding pattern of these clusters indicates these clusters have a partial ionic character. Natural electron configuration shows the extra electron is mostly localized on the metal atoms. In addition, three types of energy separations reported in this work are the adiabatic electron affinity (AEA), the vertical detachment energy (VDE), and the vertical electron affinity (VEA). Herein, adiabatic electron affinities (AEAs) and vertical detachment energies (VDEs) for all of interest are excellent consistent with experiments, as strongly supports the optimized structures. And the order of AEAs and VDEs of the (GaP) n − are both (GaP) 9 < (GaP) 8 < (GaP) 7. (GaP) 9 exhibits the lowest adiabatic electron affinity of all the clusters studied, indicating a particularly stable neutral species.