Degree Type

Dissertation

Date of Award

1991

Degree Name

Doctor of Philosophy

Department

Physics and Astronomy

First Advisor

Kai-Ming Ho

Abstract

Semiempirical interatomic potentials are developed for silicon and carbon by modeling the total energy of the system using tight-binding approaches. The parameters of the models were obtained by fitting to results from accurate first-principles Local Density Functional calculations. Applications to the computation of phonons as a function of volume for diamond-structured silicon and carbon and the thermal expansions for silicon and diamond yields results which agree well with experiment. The physical origin of the negative thermal expansion observed in silicon is explained. A tight-binding total energy model is generated capable of describing carbon systems with a variety of atomic coordinations and topologies. The model reproduces the total energy versus volume curves of various carbon polytypes as well as phonons and elastic constants of diamond and graphite. The model has also been used in the molecular-dynamics simulation of the properties of carbon clusters. The calculated ground-state geometries of small clusters (C[subscript]2-C[subscript]10) correlates well with results from accurate quantum chemical calculations, and the structural trend of clusters from C[subscript]2 to C[subscript]60 are investigated.

DOI

https://doi.org/10.31274/rtd-180813-12282

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Chunhui Xu

Language

en

Proquest ID

AAI9212205

File Format

application/pdf

File Size

84 pages

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