For magnon kicks only.
A simple way to specify momentum-transfer vectors for the calculation of
the magnetization dynamics. This variable should be used for a supercell.
For each reciprocal lattice vectors, the code will kick the original magnetization
using all the multiples of it.
The syntax reads:
N_x | N_y | N_z
and will include the (2N_x+1)(2N_y+1)(2N_z+1) multiples vectors of the reciprocal
lattice vectors of the current cell.