RELAXATION OF A SYSTEM WITH A CONICAL INTERSECTION COUPLED TO A BATH - A BENCHMARK 24-DIMENSIONAL WAVE-PACKET STUDY TREATING THE ENVIRONMENT EXPLICITLY

In this paper the phenomenon of the ultrafast relaxation of a system c oupled to a small bath is treated. The system, representing the pyrazi ne molecule, contains 4 vibrational modes and 2 electronic states coup led via a conical intersection, and the bath is a set of up to 20 harm onic oscillators. The dynamics of the complete system are described by wave packet propagation using the multiconfiguration time-dependent H artree method. By the use of multidimensional single-particle function s it was possible to obtain results of a high quality, even for the co mplete system with 24 degrees of freedom. The full wave function for t he system and bath are analyzed to reveal the characteristics of the s ystem-bath interaction, such as energy transfer to the bath, or the ef fect of the bath on the state populations. The results show that the d amping due to the bath model adopted is not only nonhomogeneous but al so selective: certain high frequencies are found to remain at long tim es.