Ab initio investigation of structures and properties of mixed silicon-potassium Si n K p and Si n K p + ( n ⩽ 6,p ⩽ 2 ) clusters

Abstract

The ${\mathrm{Si}}_{\mathit{n}}{\mathrm{K}}_{\mathit{p}}^{\mathrm{(}+\mathrm{)}}$ ( $\mathit{n}⩽6$ , $\mathit{p}⩽2$ ) clusters with different spin configurations have been systematically investigated by using the density functional theory with B3LYP. Equilibrium geometries, population analysis, binding energies, adiabatic and vertical ionization potentials as well as electric dipole moments and static dipolar polarizabilities, have been calculated and are discussed for each considered size. For the most stable isomers, the structure of the neutral ${\mathrm{Si}}_{\mathit{n}}{\mathrm{K}}_{\mathit{p}}$ and cationic ${\mathrm{Si}}_{\mathit{n}}{\mathrm{K}}_{\mathit{p}}^{+}$ clusters are found to keep the frame of the corresponding Si ${}_{\mathit{n}}$ , potassium atoms being adsorbed at the surface. The localization of the potassium cation is not the same one as that of the neutral atom. ${\mathrm{K}}^{+}$ ion is preferentially located on a Si atom while the K atom is preferentially attached at a bridge site. The population analysis show that the electronic structure of ${\mathrm{Si}}_{\mathit{n}}{\mathrm{K}}_{\mathit{p}}$ can be described as ${\mathrm{Si}}_{\mathit{n}}^{\mathit{p}-}+\mathit{p}{\mathit{K}}^{+}$ for the small sizes considered here. Binding energies and ionization potentials are compared to those of sodium and lithium-doped silicon clusters.