Defense Date

2022

Document Type

Thesis

Degree Name

Master of Science

Department

Physics and Applied Physics

First Advisor

Dr. Shiv N. Khanna

Abstract

We have investigated the Optical absorption, Infrared spectra, Binding Energies, and various other cluster properties to determine the existence of periodic trend for Transition Metal Chalcogenide Clusters ligated with CO ligands. We were motivated to answer the question of whether periodic behavior can be observed in properties of octahedral metal-chalcogenide clusters. We have used the Amsterdam Density Functional code to calculate the electronic structure of Transition Metal Chalcogenide Clusters using gradient-corrected density functional theory. We determined the existence of several periodic trends in properties of octahedral Transition Metal Chalcogenide Clusters TM6Se8(CO)6. To investigate these trends, the ground state, optical spectra, and infrared spectra of ligated transition metal chalcogenide clusters with valence electron counts ranging from 90-116 were calculated. We found that octahedral metal-chalcogenide clusters with 96, 100, and 114 have larger excitation energies, consistent with these clusters having closed-electronic shells and longer gap between the highest occupied and lowest unoccupied orbitals. Periodic trends were observed in the Infrared spectra, with the CO bond stretch having the highest energy at 100 and 114 valence electrons due to the closed-electronic shell minimizing back-bonding with the CO molecule. A periodic trend in the antisymmetric TM-C stretch was observed, with the vibrational energy increasing as the valence electron count increased. This is due to decrease in the TM-C bond length resulting in a larger force constant. These results reveal that periodic trends can be found in clusters other than simple or noble metal clusters, they can also be observed in symmetric transition-metal chalcogenide clusters.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

5-5-2022

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