FEFF is a software program used in
x-ray absorption spectroscopy
X-ray absorption spectroscopy (XAS) is a set of advanced techniques used for probing the local environment of matter at atomic level and its electronic structure. The experiments require access to synchrotron radiation facilities for their int ...
. It contains self-consistent
real space multiple-scattering code for simultaneous calculations of
x-ray
An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...
-
absorption spectra
Absorption may refer to:
Chemistry and biology
* Absorption (biology), digestion
** Absorption (small intestine)
* Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials
* Absorption (skin), a route by whic ...
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
Circular dichroism (CD) is dichroism involving circular polarization, circularly polarized light, i.e., the differential Absorption (electromagnetic radiation), absorption of left- and right-handed light. Left-hand circular (LHC) and right-hand ci ...
(XNCD), and non-resonant x-ray emission spectra. Calculations of the x-ray
scattering amplitude
In quantum physics, the scattering amplitude is the probability amplitude of the outgoing spherical wave relative to the incoming plane wave in a stationary-state scattering process.
Formulation
Scattering in quantum mechanics begins with a p ...
(
Thomson Thomson may refer to:
Names
* Thomson (surname), a list of people with this name and a description of its origin
* Thomson baronets, four baronetcies created for persons with the surname Thomson
Businesses and organizations
* SGS-Thomson M ...
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.
Uses
FEFF is used as external program to calculate basic spectra for XANES fitting using
FitIt.
Atomic scattering amplitudes and
phase shift
In physics and mathematics, the phase (symbol φ or ϕ) of a wave or other periodic function F of some real variable t (such as time) is an angle-like quantity representing the fraction of the cycle covered up to t. It is expressed in such a s ...
s are used for EXAFS fitting in IFEFFIT program suite.
References
* {{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
FEFF home page
Physics software