Description

The norm of the state out of the Chebyshev filtering depends on the polynomial order. As this is automatically updated, we do get states with fast differences in norm (observed up to 26 orders of magnitude).

This causes errors in the subspace diagonalization or not, depending on the numerical error used.

This is fixed by normalizing each state after the Chebyshev filtering, resulting in an overlap matrix with diagonal elements equal to unity, and hence a stable subspace diagonalization.