SQw
A class for the total dynamic structure factor
Calculation is done in the respective FQt object, and this is just a reference to get the correct FQt object.
- SQw.calculate_dt() float
Calculates the time separation of frames required by the experimental dataset, assuming uniform spacing. Note that this may be different from the time separation that the user has given as an input, as it only depends on the current values for
self.E
. The relationship between time and energy comes from the numpy implementation of the FFT for2 * nE
points where:\[\begin{split}\nu_{max} &=& \frac{n_E - 1}{2 n_E \Delta t} \\\\ \therefore \Delta t &=& \frac{h (n_E - 1)}{2 n_E E_{max}}\end{split}\]- Returns
The time separation required by the current values of
self.E
- Return type
- static SQw.calculate_E(nE: int, dt: float) numpy.ndarray
Calculates an array of
nE
uniformly spaced energy values from the time separation of theCompactTrajectory
frames,dt
. The frequencie are determined by the Fast Fourier Transform, as implemented by numpy, for2 * nE
points in time which we then crop to only includenE
positive frequencies. As we are dealing with frequency rather than angular frequency here, the relation to between energy is given by:\[E = h \nu\]- Parameters
- Returns
An
array
of float specifying the energy in units ofmeV
- Return type