Multidimensional Hydrogen Bond Dynamics in Salicylaldimine:  Coherent Nuclear Wave Packet Motion versus Intramolecular Vibrational Energy Redistribution

Abstract

The multidimensional wave packet dynamics of salicylaldimine following ultrafast infrared laser excitation of the OH-bending and -stretching vibrations is discussed. A seven-dimensional Cartesian reaction surface Hamiltonian in the diabatic representation is employed comprising the five skeleton normal modes which have the greatest influence on the in-plane hydrogen motion. For the numerical solution of the time-dependent Schrödinger equation the multiconfiguration time-dependent Hartree method is used. Coherent wave packet dynamics is observed after excitation of the OH-bending fundamental transition, whereas strong anharmonic mode couplings to the stretching transition cause intramolecular vibrational energy redistribution on a time scale of about 700 fs.