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# Chudley-Elliot¶

## Description¶

Models the Q dependence of the QENS line width (Gamma (hwhm)), diffusion coefficients (D), residence times (tau) and jump lengths (length) to extract the associated long range diffusive motions of molecules.

The Chudley-Elliot Jump diffusion model [1] has the form:

\[HWHM(Q) = \frac{\hbar}{\tau} \cdot \left(1 - \frac{sin(Ql)}{Ql}\right)\]

Units of \(l\) are inverse units of \(Q\).

Units of \(HWHM\) are \(meV\) if units of \(\tau\) are *ps*.
Alternatively, units of \(HWHM\) are \(\mu eV\) if units of
\(\tau\) are *ns*.

## Properties (fitting parameters)¶

Name |
Default |
Description |
---|---|---|

Tau |
1.0 |
Residence time |

L |
1.5 |
Jump length |

## References¶

**Categories**: FitFunctions | QuasiElastic

## Source¶

Python: ChudleyElliot.py