Charge transfers in mixed silicon-alkali clusters and dipole moments

Equilibrium geometries, population analysis, and electric dipole moments are compared for mixed silicon-alkali clusters SinMp (M = Li, Na and K, n ⩽ 6, p ⩽ 2) investigated by using the density functional theory. The most stable structures of SinMp are found to be similar for M = Li, Na and K. They keep the frame of the corresponding Sin, alkali atoms being adsorbed at the surface. The population analysis show that the electronic structure of SinMp can be roughly described as Sinp-+pM+ for the small sizes considered here. The evolution from M = Li to M = K of calculated dipole moments for SinM are consistent with both transferred charges from M to Si and with M-Si atomic distances.