FDMX: extended X-ray absorption fine structure calculations using the finite difference method

Jay D. Bourke (1) , Christopher T. Chantler (1) , Yves Joly (2)

1 School of Physics [Melbourne]
2 NEEL - SIN - Surfaces, Interfaces et Nanostructures

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.

Mots clés: X-ray absorption; finite difference methods; fine structure; XAFS; FDMNES; FDMX

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Jay D. Bourke, Christopher T. Chantler, Yves Joly. FDMX: extended X-ray absorption fine structure calculations using the finite difference method. Journal of Synchrotron Radiation, 2016, 23, pp.551-559. ⟨10.1107/S1600577516001193⟩. ⟨hal-01279479⟩