Ab initio study of lithiathion of the Si4(-) cluster

The potential energy surfaces of the Li(n)Si(4)(-) (n = 0-5) clusters were explored using the Kick Coalescence method. We found that, for those systems with n ≤ 2, the butterfly and parallelogram Si(4)(2-) kernels prevail as building blocks; however, when n ≥ 3, the Si(4)(4-) tetrahedral kernel, which is commonly found in heavier alkali monosilicides, MSi (M = Na, K, Rb, Cs), arises as the prevailing building block. In addition, by a natural population analysis (NPA) we found that the maximum charge transfer -4 from Li atoms to Si atoms is attained when n = 3. The addition of more Li atoms to the Si(4)(4-) system does not increase the charge transfer, but keeps it almost constant at the maximum value. We also calculated theoretical vertical electron detachment energies (VDEs) for low-lying isomers of the Li(n)Si(4)(-) (n = 0-4) clusters in order to facilitate their experimental identification.