HallRossSQE

Description

This fitting function models the dynamic structure factor for a particle undergoing jump diffusion using the Hall-Ross Jump diffusion model [1].

S(Q,E)=Height1πΓΓ2+(ECentre)2Γ=τ(1exp(l2Q22))

where:

  • Height - Intensity scaling, a fit parameter

  • Centre - Centre of peak, a fit parameter

  • Tau - Residence time, a fit parameter

  • l - Jump lengths, a fit parameter

  • Q - Momentum transfer, an attribute (non-fitting)

Units of l are inverse units of Q.

Units of HWHM are meV if units of τ are ps. Alternatively, units of HWHM are μeV if units of τ are ns.

Attributes (non-fitting parameters)

Name

Type

Default

Description

Q

WorkspaceIndex

Properties (fitting parameters)

Name

Default

Description

Height

1.0

scaling factor

Centre

0.0

Shift along the X-axis

Tau

1.25

Residence time

L

1.25

Jump length

References

Categories: FitFunctions | QuasiElastic

Source

C++ header: HallRossSQE.h

C++ source: HallRossSQE.cpp