This fitting function models the dynamics structure factor of a particle undergoing discrete jumps on N-sites evenly distributed in a circle. The particle can only jump to neighboring sites. This is the most common type of discrete rotational diffusion in a circle.
Markov model for jumps between neighboring sites:
The Decay fitting parameter is the inverse of the
transition rate. This, along with the circle radius
, conform
the two fundamental fitting parameters of the structure factor
:
The transition rate, expressed in units of energy is ,
with h = 4.135665616 meV ps.
This function is a composite of ElasticDiffRotDiscreteCircle and InelasticDiffRotDiscreteCircle.
When using DiffRotDiscreteCircle, the value of Q can be obtained either though the Q attribute or can be calculated from the input workspace using the WorkspaceIndex property. The value calculated using the workspace is used whenever the Q attribute is empty.
Methyl Rotations can be modelled setting N=3. In this case, the inelastic part reduces to a single Lorentzian:
If, alternatively, one models these dynamics using the Lorentzian function provided in Mantid:
Then:
Name | Type | Default | Description |
---|---|---|---|
N | |||
NumDeriv | |||
Q |
(integer, default=3) number of sites -
(boolean, default=true) carry out numerical derivative -
(double, default=0.5) Momentum transfer
.. properties:
.. categories::
C++ source: DiffRotDiscreteCircle.cpp (last modified: 2018-10-05)
C++ header: DiffRotDiscreteCircle.h (last modified: 2018-10-05)