Fast dynamics and high effective dimensionality of liquid fluidity

Abstract

Fluidity, the ability of liquids to flow, is the key property distinguishing liquids from solids. This fluidity is set by the mobile transit atoms moving from one quasi-equilibrium point to the next. The nature of this transit motion is unknown. Here, we show that flow-enabling transits form a dynamically distinct sub-ensemble where atoms move on average faster than the overall system, with a manifestly non-Maxwellian velocity distribution. This is in contrast to solids and gases where no distinction of different ensembles can be made and where the distribution is always Maxwellian. The non-Maxwellian distribution is described by an exponent $\alpha$ corresponding to high dimensionality of space. This is generally similar to extra synthetic dimensions in topological quantum matter, albeit higher dimensionality in liquids is not integer but is fractional. The dimensionality is close to 4 at melting and exceeds 4 at high temperature. $\alpha$ has a maximum as a function of temperature and pressure in liquid and supercritical states, returning to its Maxwell value in the solid and gas states.

arXiv comment6 pages, 4 figures

References in corpus (9)

• Topological quantum matter in synthetic dimensions
• Collective modes and thermodynamics of the liquid state
• Elementary excitations and crossover phenomenon in liquids
• Dynamical Heterogeneities Below the Glass Transition
• Transition in the supercritical state of matter: experimental evidence
• Dependence of the fragility of a glass former on the softness of interparticle interactions
• Synthetic Dimensions
• Observation of Single Transits in Supercooled Monatomic Liquids
• A General Structural Order Parameter for the Amorphous Solidification of a Supercooled Liquid