STATISTICAL-MECHANICS OF METASTABLE MATTER - SUPERHEATED AND STRETCHED LIQUIDS

Prospects are examined for modifying the conventional statistical mechanics of condensed phases to describe stretched and/or superheated metastable liquids. The representation chosen for this task is that of ''inherent structures,'' i.e., multidimensional potential minima, and their basins of attraction. By examining inherent structures for the one-dimensional Lennard-Jones system, it becomes clear that in general large-void-containing inherent structures and their basins must be removed from the canonical partition function. With an appropriate choice of maximum allowable void size, this leaves the properties of the equilibrium liquid essentially unchanged, while suppressing the vaporization transition. The void-elimination constraint causes a soft-mode instability to terminate the metastable extension of the liquid at a limit of stretching or superheating.