The calculation and interpretation of X-ray spectroscopy was revolutionised by the multiple scattering theory and the development of codes such as FEFF and MXAN. However, both of these codes, while able to describe the X-ray absorption spectra of many systems, can fail to quantitatively describe the spectra in the near-edge region associated with the XANES spectrum. This is associated with the breakdown of the muffin tin approximation which underpins these codes.

The aim of FDMNES is to provide a user friendly code, which is able to simulate a broad range of x-ray spectroscopies, beyond the muffin tin approximation. This ab initio (first principles) approach which is based upon the finite difference method, aims to eliminate all methodological parameters and go beyond the limitations of the spherical muffin tin approximation. It includes density functional theory and time-dependent density functional theory.

Important literature references can be found at:

Y. Joly  Physical Review B 63, 125120-125129 (2001).

O. Bunau and Y. Joly  Journal of Physics: Condensed Matter 21, 345501 (2009).

The presentation on FDMNES made during the workship can be found here:

Y. Joly - Simulation of X-Ray Absorption Spectroscopies with FDMNES‌

A workshop version of the code with many worked examples can be found here on the project website, available for download under the heading XANES Practical. 

For more details see the FDMNES project homepage. 

Repository of Examples Here.