The study of the electronic structures and properties of pure and transition metal-doped silicon nanoclusters: a density functional theory approach

Abstract

This report presents the study of ab initio electronic structure and properties of pure and transition metal (TM = Ti, Zr and Hf)-doped silicon clusters, TM@Si(n), by using density functional theory with a polarised basis set (LanL2DZ) within the spin-polarised generalised gradient approximation for different values of n varying from 8 to 20. As the first step of the study, different optimised geometries of pure and doped clusters are calculated. These optimised clusters are then used to calculate different structural and physical parameters of the clusters, like binding energy, Highest Occupied Molecular Orbital – Lowest Unoccupied Molecular Orbital (HOMO–LUMO) gap, charge transfer, etc. In order to check the stability of the clusters, the second-order difference in the energy of the optimised structures is calculated. To study the optical behaviour of the clusters, infrared and Raman spectra are also calculated. Further calculations are also done on cation and anion clusters of both pure and doped nanoclusters to obtain their ionisation potential, electron affinity and chemical potential. An effort has been made to correlate the variation of different calculated parameters with the size of the clusters to explain the real existence and stabilities of different TM-doped clusters.