Does the Sastry transition control cavitation in simple liquids?

Abstract

We examine the Sastry (athermal cavitation) transitions for model monatomic liquids interacting via Lennard-Jones as well as shorter- and longer-ranged pair potentials. Low-temperature thermodynamically stable liquids have ρ < ρS except when the attractive forces are long-ranged. For moderate- and short-ranged attractions, stable liquids with ρ > ρS exist at higher temperatures; the pressures in these liquids are high, but the Sastry transition may strongly influence their cavitation under dynamic hydrostatic expansion. The temperature T* at which stable ρ > ρS liquids emerge is ∼0.84ϵ/kB for Lennard-Jones liquids; T* decreases (increases) rapidly with increasing (decreasing) pair-interaction range. In particular, for short-ranged potentials, T* is above the critical temperature. All liquids' inherent structures are isostructural (isomorphic) for densities below (above) the Sastry density ρS. Overall, our results suggest that the barriers to cavitation in most simple liquids under ambient conditions for which significant cavitation is likely to occur are primarily vibrational-energetic and entropic rather than configurational-energetic. The most likely exceptions to this rule are liquids with long-ranged pair interactions, such as alkali metals.