  The effect of chaotic bath dynamics on the decoherence of a quantum system is
examined for the vibrational degrees of freedom of a diatomic molecule in a
realistic, constant temperature collisional bath. As an example, the specific
case of I$_2$ in liquid xenon is examined as a function of temperature, and the
results compared with an integrable xenon bath. A crossover in behavior is
found: the integrable bath induces more decoherence at low bath temperatures
than does the chaotic bath, whereas the opposite is the case at the higher bath
temperatures. These results, verifying a conjecture due to Wilkie, shed light
on the differing views of the effect of chaotic dynamics on system decoherence.
