radtools.MagnonDispersion.B

method

MagnonDispersion.B(k)

Computes B(k) matrix.

\[B(\boldsymbol{k})^{ij} = \dfrac{\sqrt{S_i\cdot S_j}}{2}\boldsymbol{u}^T_i\boldsymbol{J}_{i,j}(-\boldsymbol{k})\boldsymbol{u}_j\]

where indices \(i\) and \(j\) correspond to the atoms in the exchange pair.

Parameters:

k(3,) array-like

Reciprocal vector. In absolute coordinates.