Clearly, the reference weight is an empirical diagnostic measure, and therefore there is no universal threshold that unambiguously classifies Ψ as affected by intruder states. Typical values of w ref for small organic molecules range between 0.7 and 0.9, while transition metal complexes with many open-shell electrons can have lower values due to the dense manifold of electronic states and the presence of a large number of important low-lying configurations.