spinw.coupling property

stores the list of bonds

dl: Distance between the unit cells of two interacting spins, stored in a $[3\times n_{coupling}]$ matrix.
atom1: First magnetic atom, pointing to the list of magnetic atoms in the list generated by spinw.matom, stored in a row vector with $n_{coupling}$ element.
atom2: Second magnetic atom, same as atom1.
mat_idx: Stores pointers to matrices for every coupling in a $[3\times n_{coupling}]$ matrix, maximum three matrix per coupling (zeros for no coupling) is allowed.
idx: Neighbor index, increasing indices for the equivalent couplings, starting with 1,2,… which means first and second neighbor bonds, respectively.
type: Type of coupling corresponding to mat_idx matrices. Default is 0 for quadratic exchange, type = 1 for biquadratic exchange.
sym: If true the bond symmetry operators will be applied on the assigned matrix.
rdip: Maximum distance until the dipolar interaction is calculated. Zero value means no dipolar interactions are considered.
nsym: The largest bond idx value that is generated using the space group operators. Typically very long bonds for dipolar interactions won’t be calculated using space group symmetry.