Investigating the Vibrational Properties of Hexagonal Close-Packed Solids Using an Embedded-Atom-Method Model

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USU Student Showcase

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D. Mark Riffe


The embedded-atom-method model (EMB) allows the prediction of vibrational properties of a material based on a chosen formulation for pair potentials and embedding energies. Several EAM models have given results with varying accuracy for specific geometries, but work performed in 2012 by R B Wilson and D M Riffe [1] has lead to the formation of a model that describes the bulk and surface properties of both body-centered cubic (BCC) alkali metals and face-centered cubic (FCC) materials to greater experimental agreement than preceding models, using a set of custom Matlab programs. We build on that success by attempting to extend the program to accommodate the hexagonal close-packed (HCP) structure as well, determining whether the model is so robust as to accurately predict vibrational dynamics of additional geometries.

In addition to and in preparation for these extended capabilities, the existing Matlab programs have been heavily reorganized to improve readability, usability, flexibility, and efficiency, combining their functionalities into a single program that can be extended more easily. Building on that, we will be able to accept HCP materials and should be able to predict such properties as surface relaxation, frequency density-of-states (DOS), directional dispersion curves, and many other thermal properties. The degree of agreement with experiment can then be considered to evaluate the success of the Wilson-Riffe model beyond its initial scope.
[1] Wilson R B and Riffe D M 2012 J. Phys.: Condens. Matter 24 335401

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