neutron-scattering-no-lattice

Calculates the partial scattering cross section for systems without a Bravis lattice.

\[\begin{split}\frac{d^2\sigma}{d\Omega dE} &= \frac{\left(\gamma r_0\right)^2}{2\pi\hbar} \frac{k_1}{k_0} \sum_{\alpha\beta}\left( \delta_{\alpha\beta} - \tilde{Q}_{\alpha}\tilde{Q}_{\beta}\right) \\ &\times f(\vec{Q})^2 \left\langle \overline{\hat{S}^{\alpha}(\vec{Q},\omega)} \hat{S}^{\beta}(\vec{Q},\omega) \right\rangle\end{split}\]

Warning

This monitor current only supports a single material.

Optional settings

kvector

periodogram

The frequencies are calculated using Welch’s method of overlapping periodograms.

• length (int | 1000): number of outputs over which to calculate periodogram (i.e. output_steps x timesteps)

• overlap (int | 500): number of outputs to overlap in sequential periodogram

periodogram : {
  length = 1000;
  overlap = 500;
};

form_factor

form_factor = (
  {
    g  = [2.0, 0.0, 0.0, 0.0];
    j0 = (0.3972, 13.244, 0.6295, 4.903, -0.0314, 0.350, 0.0044);
  }
);

polarizations

List of arrays of neutron polarisation vectors.

polarizations = (
  [0.0, 0.0, 1.0],
  [0.0, 0.0,-1.0]
);