# FEFF Variables

### From FEFF

## Contents |

## Variables in the EXAFS and XANES formulae

## *k*

The wave number in units of . where is energy and is the Fermi level computed from electron gas theory at the average interstitial charge density.

## χ(*k*)

## φ_{c}

The total central atom phase shift,

## *F*_{eff}

The effective curved-wave backscattering amplitude in the EXAFS formula for each shell.

## φ_{eff}

The phase shift for each shell

The total central atom loss factor,

## R

The distance to the central atom for each shell

## N

The mean number atoms in each shell

## σ^{2}

The mean square fluctuation in R for each shell

## λ

The mean free path in Å,

## *k*_{f}

The Fermi momentum at the average interstitial charge density

## *p*(*r*)

The local momentum,

## Σ(*E*)

The energy dependent self energy at energy E, is the self energy at the Fermi energy.

## μ(*E*)

The total absorption cross-section

## μ_{0}(*E*)

The embedded atomic background absorption

### FEFF Input and Output Files

- Intermediate output files
- Diagnostic files
- Main output data
**Variables in the EXAFS and XANES formulae**