SEARCH Articles Figures Tables A levels A two-level system A-coupling Coupled system Jahn pseudo- Jahn system Jahn-Teller Jahn-Teller coupling Jahn-Teller splittings Jahn-Teller system Jahn-Teller-splitting Level splitting Leveling system Pseudo-tunnelling Split couplings Split system Splitting system System-level Tunnel splitting Tunneling coupling Tunneling splitting Two level