For a general polyatomic molecule, the classical phase space at some fixed energy and angular momentum is divisible into two regimes: a quasiperiodic and a stochastic (or chaotic) regime. In certain molecules - those having symmetrically equivalent X-H bonds, where X is any heavy atom - the classical trajectories comprising the quasiperiodic regime can be subdivided into two classes: normal trajectories, for which the time-averaged amplitudes in all the X-H stretching vibrations are equivalent, and local trajectories, which exhibit a permanent imbalance in the amplitudes of the various X-H stretching vibrations. We report here the development of trajector diagnostics for bound, nonseparable motion to distinguish normal, local, and stochastic types of motion in systems with more than two internal (coordinate) degrees of freedom, and the application of these diagnostics to determine the numbers of normal, local, and stochastic states of a realistic model of nonrotating H/sub 2/O as functions of energy. This application is the first such study for a real polyatomic molecule.
