title: FDMX: extended X-ray absorption fine structure calculations using the finite difference method.
abstract: A new theoretical approach and computational package, FDMX, for general calculations of X-ray absorption fine structure (XAFS) over an extended energy range within a full-potential model is presented. The final-state photoelectron wavefunction is calculated over an energy-dependent spatial mesh, allowing for a complete representation of all scattering paths. The electronic potentials and corresponding wavefunctions are subject to constraints based on physicality and self-consistency, allowing for accurate absorption cross sections in the near-edge region, while higher-energy results are enabled by the implementation of effective Debye-Waller damping and new implementations of second-order lifetime broadening. These include inelastic photoelectron scattering and, for the first time, plasmon excitation coupling. This is the first full-potential package available that can calculate accurate XAFS spectra across a complete energy range within a single framework and without fitted parameters. Example spectra are provided for elemental Sn, rutile TiO2 and the FeO6 octahedron.
authors.affiliation: School of Physics, University of Melbourne, Australia.
authors.forename: Jay D
authors.initials: JD
authors.lastname: Bourke
authors.affiliation: School of Physics, University of Melbourne, Australia.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Chantler
authors.affiliation: Université Grenoble Alpes, Institut NÉEL, F-38042 Grenoble Cedex 9, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Joly
keywords: FDMNES; FDMX; X-ray absorption; XAFS; fine structure; finite difference methods