FEFF (software)

FEFF is a real-space multiple scattering code used to calculate x-ray absorption spectra (XAS), x-ray magnetic circular dichroism (XMCD), and related electronic structure properties of materials. It is based on the real-space multiple scattering theory, which takes into account the scattering of photoelectrons by atoms surrounding the absorbing atom.

The code allows for the calculation of XAS and XMCD spectra for a wide variety of materials, including crystalline solids, surfaces, and molecules. It can be used to determine the local atomic and electronic structure around the absorbing atom, providing insights into the chemical bonding, coordination environment, and magnetic properties of the material.

FEFF incorporates various approximations and features, including self-consistent field calculations, core-hole effects, and Debye-Waller factors to account for thermal disorder. It is often used in conjunction with other computational tools for materials characterization and analysis. The output of FEFF can be used to interpret experimental XAS and XMCD data, providing a detailed understanding of the material's properties.