How can I understand if my system has degenerate electronic configuration? I'm running some post-HF methods and in the meanwhile try to understand which is the most accurate method for my system. However, reading about Coupled-Cluster method it is usually reported that this method is not adequate for studying systems with degenerate or nearly degenerate electronic configuration. As far as I understood this means, for instance, that the excited state could be near in energy to another excited state that differs only for some orbital occupation, but how can I check this situation?