Master of Science (MSc)
Faculty of Science
Dr. Ian P Hamilton
A plethora of work has been done in the area of nanoparticles of late due to the fact that chemists (and physicists) have discovered that the properties of nanoparticles differ from both those of the bulk material and the atoms themselves. Nanoparticles have become of high interest for the use as catalysts while materials like graphene, being only one atom thick, have been shown to be great electrical conductors in comparison with the 3D structure of diamond. Among these peculiar nanoscale properties is the phenomenon of nanochirality, where a nanoparticle can exhibit chirality that does not extend to the macroscale of the material in the bulk phase. This property has mostly been seen without outside influence, known as intrinsically, in metal nanoparticles whereby no chiral information had been involved, however the synthetic approach to obtain this property has predominately been with the use of chiral ligands that then induce chirality into the system. In the case of ligand-protected semiconducting nanocrystals, typically referred to as quantum dots, nanochirality has only been observed intrinsically in one instance but has been induced using chiral ligands and polarized light during synthesis. The aim of this thesis is to use density functional theory calculations to show that intrinsic chirality in quantum dots exists. This is a study of a 26 atom II-VI semiconductor system which has been capped with a variety of achiral charge stabilizing ligands that induce chirality into the system. Geometry optimizations and ab initio molecular dynamics calculations show that the chiral structure generally has a significantly lower energy than the achiral tetrahedral counterpart. Furthermore, the effects of these ligands were studied using time-dependent density functional theory calculations that simulated both circular dichroism and absorbance spectra. This work contributes to the field of science as a whole as not only iii does it provide insight into the fundamental properties of matter on the nanoscale but also has a broad range of potential applications dependent on the HOMO-LUMO gap that these structures possess.
Edwards, Richard, "A Density Functional Theory Study of Intrinsically Chiral Semiconductor Nanocrystals" (2017). Theses and Dissertations (Comprehensive). 1999.