Effective Hamiltonian for femtosecond vibrational dynamics.
Time propagation of zero-order states of an effective spectroscopic Hamiltonian is tested against femtosecond time dependent dynamics of adiabatic wavepackets evolving on a model potential energy surface for two coupled modes of the radical HO(2) with multiple potential wells and above barrier motion. A generalized Hamiltonian which breaks the usual conserved polyad action by including extra resonance couplings (V(2:1) and V(3:1)) successfully describes the time evolution after the further addition of two "ultrafast" couplings. These new couplings are a nonresonant coupling a(1)a(2)+a(1)(†)a(2)(†) and a resonant coupling V(1:1) that functions as an ultrafast term because the system is far from 1:1 frequency resonance.
Institute of Theoretical Science, University of Oregon, Eugene, Oregon 97403, USA.
George L
GL
Barnes
Michael E
ME
Kellman