Structure of Small Gold Clusters with Si Doping Using DFT (AunSi, n=1-10, 19)

Abstract

The structures of silicon doped gold clusters AunSi (n = 1-10 and 19) have been investigated using first principle calculations based on density functional theory (DFT). Calculations indicate that the stability of a gold cluster increases with the introduction of a Si atom. In all the low lying geometries, Si prefers peripheral positions. For every ground state configuration with n > 3 (n = 6 and 9 being exceptions) Si has tetra-coordination. In almost all of the tetra coordinated geometries the coordination unit including Si, is in the form of a square pyramid with gold atoms forming the square base. Electronic properties such as HOMO-LUMO gap, ionization potential and electron affinity have also been calculated and support the relative stability of clusters with even n. The study of Au20 cage doped with Si atom has been done .Similar to smaller Si doped gold clusters; the Si atom prefers an exohedral position. The doping of Si atom has enhanced the stability and chemical reactivity of Au20 cluster.