Relativistic Jahn-Teller and pseudo-Jahn-Teller couplings in D2d systems

► Interplay of Jahn-Teller (JT) and spin-orbit couplings in D2d systems. ► 2E×e Jahn-Teller effect of relativistic origin. ► Relativistic pseudo-JT couplings of 2E and 2B states via b1, b2 and e modes.