Derivation of Many Body Potentials to Reproduce Elastic and Vibrational Qualities of FCC and BCC Metals
One of the great advantages of the local density methods of materials simulation (Daw and Baskes, 1984; Finnis and Sinclair, 1984) over simple pair potentials is their ability to model such things as elastic properties and defect properties in regions of low symmetry with a degree of computational difficulty only approximately twice that involved in pair models. Although the model itself is conceptually simple, it can be quite difficult to implement owing to the effort involved in deriving the functions necessary to accurately describe the material of interest. This task is even more daunting when an alloy system is under investigation, in which case the functions must reproduce not only the empirically observable qualities of the pure materials, but also such things as the heat of formation and stable structure of the alloys of interest. Several authors have undertaken to investigate an assortment of alloys with a variety of functions derived specifically for that purpose. In general, the functions so derived are not useful in conjunction with any other materials. This necessitated, for example, the derivation of new nickel functions for use with nickel-aluminum alloys (Foiles and Daw, 1987) even after a set of nickel functions had already been derived which were compatible with copper, silver, gold, platinum, and palladium (Foiles et al., 1986).
KeywordsElastic Constant Pair Potential Phonon Frequency Phonon Dispersion Curve Vacancy Formation Energy
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