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The development of novel models to further the understanding of nanoscale material dynamics
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The development of novel models to further the understanding of nanoscale material dynamics

Evan Michael Curtin
Master of Science (M.S.), Drexel University
01 Jul 2015
DOI:
https://doi.org/10.17918/etd-6509
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Abstract

Chemistry Chemistry, Physical and theoretical Nanotechnology
Two models are presented to understand the dynamics of nanoscale materials. The first is a classical physics based coupled torsion spring model, which can be applied to determine torsional vibrational frequencies in branched molecules. The second is an extension of a probabilistic method for determining quantum particle transit times to a system of any number of states. The first model is shown to reproduce torsional vibrational frequencies in branched hydrocarbons in agreement with AM1 and HFSCF calculations towards the onset of the nano-regime. The model is then extrapolated to systems far too large to be subject to quantum chemistry based techniques and shows asymptotic behavior different from simple harmonic oscillator models. This model can help in understanding the vibrational behavior of systems at the nanoscale. The second method developed is a generalization of a probabilistic approach to the quantum transit time problem. While the method has been previously produced for a two state system, this work presents a novel way to determine transit times for a quantum particle in a system of 3 or more states. The model is applied to a triple well potential as a model for molecular donor-bridge-acceptor systems. The recovered transit times are in agreement with previously computed values, demonstrating the validity of the approach.

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