Date of Award

2008-01-01

Degree Name

Master of Science

Department

Physics

Advisor(s)

Tunna Baruah

Abstract

ABSTRACT

The small clusters (aggregates of atoms containing a few tens of atoms) of semiconductors and metals often adopt very different shapes than the fragments of these materials in the bulk phase. Due to their large surface to volume ratio and unsaturated bonds, the small clusters often have properties that are very different from their bulk. Semiconductor clusters are extensively studied for their potential applications in a wide variety of systems from opto-electronic devices to spintronics. The present work is devoted to understanding the structural and electronic properties of small clusters of the zinc sulfide ZnnSn where n = 1 - 6. The equilibrium structures of the clusters are obtained by starting with several possible atomic configurations and optimizing these geometries. The calculations are performed using density functional theory. The calculations are carried out using advanced electronic structure package called NRLMOL. The calculations are free from pseudo potential approximation i.e. both valence as well as core electrons are explicitly treated in calculations. The nature of each local minimum (structure) is analyzed by computing the vibrational frequencies within the harmonic approximation. The electronic properties such as ionization energies, the band gap (HOMO-LUMO gap), and electron affinity are obtained for all the stable structures. Additionally, spectroscopic properties such as infrared and Raman spectra are obtained which will be helpful in possible detection and identification of these clusters in experiment. The evolutions of all these properties are studied as a function of the size of clusters.

Language

en

Provenance

Received from ProQuest

File Size

77 pages

File Format

application/pdf

Rights Holder

Venkata Ramana Chaganti

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