  Time-dependent renormalization was employed to derive a nonlinear quantum
master equation (QME), in which the dynamics of a non-equilibrium fluctuation
in an irrelevant system are fed back into that of a relevant one. In terms of
application, the nonlinear QME was formulated from the viewpoint of the
conventional theory for weak electronic coupling and analyzed numerically. In
the case of a large energy gap between sites in the relevant system and the
reorganization energy, the new equation reproduced the results obtained through
numerically exact calculations; this behavior is in contrast with that of the
conventional theory.
