Jahn-Teller and spin-orbit coupling effects in transition-metal trifluorides

► Jahn-Teller potential-energy surfaces of 5E′ states of MnF3 and CoF3 calculated. ► The JT coupling parameters have been determined up to sixth order. ► Vibronic spectra computed with two-mode JT Hamiltonian including spin-orbit coupling. ► First ab initio study of the dynamical JT effect in transition-metal trifluorides.