Date of Award
Doctor of Philosophy
Physics and Astronomy
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.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Xu, Chunhui, "Theoretical study of the structure, energetics, and dynamics of silicon and carbon systems using tight-binding approaches " (1991). Retrospective Theses and Dissertations. 9789.