Ab initio MO study of solvated negative alkali atom clusters: [M(H2O)(n)](-) and [M(NH3)(n)](-) (M=Na and Li, n=1-3)

The structures, stabilities and vertical electron detachment energies (VDEs) of [Na(H2O)(n)](-), [Na(NH3)(n)](-) and [Li(NH3)(n)](-) (n = 1-3) are investigated by the ab initio MO method at the correlated level. The Na-H interactions and hydrogen bonds are important in [Na(H2O)(n)](-), while the metal-N bonds become essential in stabilizing the [Na(NH3)(n)](-) and [Li(NH3)(n)](-) with increasing n. The size dependence of the VDEs of [Na(H2O)(n)](-) differs from that of [Na(NH3)(n)](-) and [Li(NH3)(n)](-) due to their structural features. In addition, the geometries and VDEs of [Li(H2O)(n)](-) (n = 1-3) are predicted theoretically. The size dependence of their VDEs is similar to that of [Na(NH3)(n)](-) and [Li(NH3)(n)](-) rather than [Na(H2O)(n)](-).