The quantum dynamics of coupled subsystems connected to a thermal bath is s
tudied. In some of the earlier work the effect of intercenter coupling on t
he dissipative part was neglected. This is equivalent to a zeroth-order per
turbative expansion of the damping term with respect to the intercenter cou
pling. It is shown numerically for two coupled harmonic oscillators that th
is treatment can lead to artifacts and a completely wrong description, for
example, of a charge transfer processes even for very weak intercenter coup
ling. Here we perform a first-order treatment and show that these artifacts
disappear. In addition, we demonstrate that the thermodynamic equilibrium
population is almost reached even for strong intercenter coupling strength.
(C) 2001 Elsevier Science B.V. All rights reserved.