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# ElasticDiffSphere¶

## Description¶

This fitting function models the elastic part of the dynamics structure factor of a particle undergoing continuous diffusion but confined to a spherical volume, ElasticDiffSphere.

\[S(Q,E\equiv \hbar \omega) = (3 \frac{j_1(QR)}{QR})^2(Q\cdot R) \delta (\omega)\]

Because of the spherical symmetry of the problem, the structure factor is expressed in terms of the \(j_l(z)\) spherical Bessel functions.

## Attributes (non-fitting parameters)¶

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

Q |
|||

WorkspaceIndex |

\(Q\) (double, default=1.0) Momentum transfer

## Properties (fitting parameters)¶

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

Height |
1.0 |
Scaling factor to be applied to the resolution. |

Centre |
0.0 |
Shift along the x-axis to be applied to the resolution. |

Radius |
2.0 |
Sphere radius |

**Categories**: FitFunctions | QuasiElastic

## Source¶

C++ header: ElasticDiffSphere.h

C++ source: ElasticDiffSphere.cpp