| Timescales and pathways of vibrational energy redistribution (IVR) in benzene were investigated using classical and quantum dynamical methods; the CH(v = 2) overtone was the focus of the studies because of the non-trivial nature of IVR resulting from these initial conditions. The most extensive ab initio force field available for a polyatomic molecule was employed; 15-mode, 21-mode, and 30-mode models of benzene were used. Local mode analyses indicate that the following modes are activated in sequence: ipso out-of-plane CH bend, ipso in-plane CH wag, adj CC stretch, term CC stretch, ortho in-plane CH wag, meta in-plane CH wag, int CC stretch, meta CH stretch, para in-plane CH wag , and para CH stretch. Normal mode analyses indicate that modes with the most in-plane CH wag character are most important in IVR; modes with dominant CCC bend character are not at steady state even by 9.6 ps. The most important out-of-plane normal modes in IVR have the greatest amounts of out-of-plane CH bend character. Energy partitioning at 9.6 ps can be adequately described by at least two statistical models. |
