{{multiple issues| {{context|date=November 2013}} {{too technical|date=November 2013}} }}'''FEFF''' is a software program used in x-ray absorption spectroscopy. It contains self-consistent real space multiple-scattering code for simultaneous calculations of x-ray-absorption spectra and electronic structure. Output includes extended x-ray-absorption fine structure (EXAFS), full multiple scattering calculations of various x-ray absorption spectra (XAS) and projected local densities of states (LDOS). The spectra include x-ray absorption near edge structure (XANES), x-ray natural circular dichroism (XNCD), and non-resonant x-ray emission spectra. Calculations of the x-ray scattering amplitude (Thomson and anomalous parts) and spin dependent calculations of x-ray magnetic circular dichroism (XMCD) and spin polarized x-ray absorption spectra (SPXAS and SPEXAFS) are also possible, but less automated.
The most recent version of FEFF is FEFF10, released in 2020.<ref>{{Cite web|url=https://times-software.github.io/feff10/|title = Feff10}}</ref>
==Uses== FEFF is used as external program to calculate basic spectra for XANES fitting using FitIt.
Atomic scattering amplitudes and phase shifts are used for EXAFS fitting in IFEFFIT program suite.
==References== {{Reflist}} * {{cite journal | last1=Ankudinov | first1=A. L. | last2=Ravel | first2=B. | last3=Rehr | first3=J. J. | last4=Conradson | first4=S. D. | title=Real-space multiple-scattering calculation and interpretation of x-ray-absorption near-edge structure | journal=Physical Review B | publisher=American Physical Society (APS) | volume=58 | issue=12 | date=1998-09-15 | issn=0163-1829 | doi=10.1103/physrevb.58.7565 | pages=7565–7576| bibcode=1998PhRvB..58.7565A | url=https://zenodo.org/record/1233737 }}
==External links== *[http://monalisa.phys.washington.edu/feffproject-feff.html FEFF home page]
Category:Physics software