spin_moment

sisl.physics.electron.spin_moment(state, S=None, projection='diagonal')[source]

Spin magnetic moment (spin texture) and optionally orbitally resolved moments

This calculation only makes sense for non-colinear calculations.

The returned quantities are given in this order:

Spin magnetic moment along \(x\) direction
Spin magnetic moment along \(y\) direction
Spin magnetic moment along \(z\) direction

These are calculated using the Pauli matrices \(\boldsymbol\sigma_x\), \(\boldsymbol\sigma_y\) and \(\boldsymbol\sigma_z\):

\[\begin{split}\mathbf{S}_\alpha^x &= \langle \psi_\alpha | \boldsymbol\sigma_x \mathbf S | \psi_\alpha \rangle \\ \mathbf{S}_\alpha^y &= \langle \psi_\alpha | \boldsymbol\sigma_y \mathbf S | \psi_\alpha \rangle \\ \mathbf{S}_\alpha^z &= \langle \psi_\alpha | \boldsymbol\sigma_z \mathbf S | \psi_\alpha \rangle\end{split}\]

If projection is orbitals/basis/true, the above will be the orbitally resolved quantities.

Parameters:

state (ndarray) – vectors describing the electronic states, 2nd dimension contains the states
S (ndarray, optional) – overlap matrix used in the \(\langle\psi|\mathbf S|\psi\rangle\) calculation. If None the identity matrix is assumed. The overlap matrix should correspond to the system and \(\mathbf k\) point the eigenvectors has been evaluated at.
projection (Union[ProjectionTypeTrace, ProjectionTypeDiag, ProjectionTypeHadamard, True, False]) – how the projection should be done

Notes

This routine cannot check whether the input eigenvectors originate from a non-colinear calculation. If a non-polarized eigenvector is passed to this routine, the output will have no physical meaning.