degenerate_decouple

sisl.physics.degenerate_decouple(state, M)

Return vec decoupled via matrix M

The decoupling algorithm is this recursive algorithm starting from $i=0$:

$$\begin{array}{rl}\mathbf{p}& ={\mathbf{V}}^{†}{\mathbf{M}}_i\mathbf{V}\\ \mathbf{p}\mathbf{u}& =\mathit{\lambda }\mathbf{u}\\ \mathbf{V}& ={\mathbf{u}}^T\mathbf{V}\end{array}$$

Parameters:

• state (numpy.ndarray or State) – states to be decoupled on matrices M The states must have C-ordering, i.e. [0, ...] is the first state.

• M (numpy.ndarray) – matrix to project to before disentangling the states