Quantum dynamics of intramolecular vibrational energy redistribution for initally excited CC ring modes in 30-mode benzene

Energy flow from four CC ring-mode bright states (A1g , B2u , E1u , and E2g ) was examined for the CC(v=2) overtone. The A1g normal mode exhibits completely reversible intramolecular vibrational energy redistribution (IVR) over the course of the dynamics (9.6 ps); energy flow out of the initially excited mode is less complete but less reversible for the B2u and E2g modes, however. IVR pathways from the E1u and E2g states are quite different and show the E1u state losing more than 50% of the initial energy while the E2g state retains more than 90% of this quantity. In all cases, the in-plane CCC bending modes and out-of-plane modes do not significantly contribute to IVR.