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# InelasticDiffSphere¶

## Description¶

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

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

The value of the momentum transfer can be obtained either through attribute \(Q\), or can be calculated from the input workspace using attribute \(WorkspaceIndex\). The value calculated using the workspace is used whenever attribute \(Q\) is set empty.

## Attributes (non-fitting parameters)¶

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

Q |
|||

WorkspaceIndex |

\(Q\) (double, default=1.0) Momentum transfer - \(WorkspaceIndex\) (integer, default=0)

## Properties (fitting parameters)¶

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

Intensity |
1.0 |
scaling factor |

Radius |
2.0 |
Sphere radius, in Angstroms |

Diffusion |
0.05 |
Diffusion coefficient, in units of A^2*THz, if energy in meV, or A^2*PHz if energy in ueV |

Shift |
0.0 |
Shift in domain |

**Categories**: FitFunctions | QuasiElastic

## Source¶

C++ header: InelasticDiffSphere.h

C++ source: InelasticDiffSphere.cpp