Dissipative multistate systems in the scaling limit

The dynamics of dissipative multistate systems is studied using integral eq uations that are derived within the framework of the path integral-formulat ion of quantum mechanics. As an illustrative example we study a 5-state sys tem coupled to a harmonic reservoir with an Ohmic spectral density with a h igh cutoff frequency. The dominant exchange mechanism determining the dynam ics as well as the range of validity of different approximations to the inf luence functional are investigated. Besides depending on temperature and th e strength of the system-bath coupling, both the exchange mechanism and the accuracy of different approximations to the influence functional depend on the state in which the system is initially prepared. [S1063-651X(99)07307- 9].