  A recent proposal for practical calculation of vibrational mode lifetimes is
tested on simple, low-dimensional anharmonic models. The proposed scheme
approximates the mode lifetime in terms of ensemble averages of specific
functions in phase-space; various levels of approximation correspond to
ensemble moments of the Liouvillian. It is shown that, for systems where the
vibrational density of states is well-approximated by a single broadened peak,
the fourth-moment approximation works well over the full range of temperature.
