Theoretical Study of the Effect of Simultaneous Doping with Silicon, on Structure and Electronic Properties of Adamantane

Abstract

In this paper, structural and electronic properties of adamantane (C₁₀H₁₆) and its Si-doped derivatives were calculated using density functional theory. In order to find diamondoids with specific properties, one to ten carbon atoms of adamantane were substituted with silicon atoms and the changes in structural and electronic properties of adamantane after substituting were investigated. HOMO-LUMO energies of 1–10 Si-doped adamantane and their gaps were calculated and the parameters that affect on the energy gaps of Si-doped structures were introduced. Among the doped molecules, 4-Si doped adamantane with high symmetry structure shows distinct properties. Adiabatic electron affinity and ionization potentials were calculated using Gibbs free energies of cationic and anionic forms of all structures. The results show that the electron affinity of adamantane is negative and reduces to positive values by simultaneous C/Si doping in 7–10-sila-doped adamantane. These results show the vacuum level transfer from above to below the conduction band. NBO charge analyses were also applied for describing the electron affinity and Ionization potential results.