Symmetry-adapted excited states for the T-1u circle times h(g) Jahn-Tellersystem - art. no. 075102

Jahn-Teller (JT) systems typically contain a set of equivalent-energy wells in the lowest adiabatic potential-energy surface (APES). Quantum-mechanica l tunneling between these wells (the dynamic JT effect) must be allowed for by taking appropriate symmetrized combinations of oscillator-type states a ssociated with the wells. It is important to be able to describe the excite d states of such systems for a number of reasons. One particular reason is that they are required for the calculation of second-order vibronic reducti on factors, which in turn are useful for modeling experimental data using e ffective Hamiltonians. In this paper, projection-operator techniques are us ed to obtain general expressions for the symmetry-adapted excited states of the icosahedral T-1u circle timesh(g) JT system for the case of D-5d minim a in the APES. Analytical expressions for the states and their energies for one-phonon excitation are given explicitly. The energies of a selection of states with two-phonon excitations are also obtained and plotted. The resu lts obtained in this paper are applicable to the C-60(-) molecule.