Multiscale Modeling of Chalcogenides

Date

2006-03

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New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering.

Abstract

Chalcogenide glasses exhibit properties applicable to a wide range of fields, including electrical and optical switching and the transmission of infrared radiation. In this thesis, we adopt a hierarchical multiscale modeling approach to investigate the fundamental physics of chalcogenide systems. Our multiscale modeling begins in Part I at the quantum mechanical level, where we use the highly accurate Møller-Plesset perturbation technique to derive interaction potentials for elemental and heterogeneous chalcogenide systems. The resulting potentials consist of two-, three-, and effective four-body terms. In Part II, we use these ab initio derived potentials in classical Monte Carlo simulations to investigate the structure of chalcogenide glasses. We discuss our simulation results in relation to the Phillips model of topological constraints, which predicts critical behavior in chalcogenide systems as a function of average coordination number. Lastly, in Part III we address the issue of glass transition range behavior. After reviewing previous models of the glass transition, we derive a new model based on nonequilibrium statistical mechanics and an energy landscape formalism. The new model requires as input a description of inherent structure energies and the transition energies between these structures. To address this issue, we derive an eigenvector-following technique for mapping a multidimensional potential energy landscape. This technique is then extended for application to enthalpy landscapes. Our model will enable the first-ever calculation of glass transition behavior based on only ab initio derived physics.

Description

Advisory committee members: Alexis Clare, Roger Loucks, Doreen Edwards. Dissertation completed in partial fulfillment of the requirements for the degree of Doctorate of Philosophy in Glass Science at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University

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