Comment on the Theory of Extended X-Ray-Absorption Fine Structure

The two theoretical approaches to extended x-ray-absorption fine structure, based on either "long-range order" or "short-range order" are critically examined within a muffin-tin-scatterer model. It is argued that the two apparently dissimilar theories will in practice yield essentially the same results. The argument is based on the implications of recent multiple scattering calculations on clusters of atoms.