Behavior of Supercritical Fluids across the “Frenkel Line”
Authors: Bryk T., Gorelli FA., Mryglod I., Ruocco G., Santoro M., Scopigno T.
Autors Affiliation: Natl Acad Sci Ukraine, Inst Condensed Matter Phys, 1 Svientsitskii St, UA-79011 Lvov, Ukraine; Lviv Polytech Natl Univ, Inst Appl Math & Fundamental Sci, UA-79013 Lvov, Ukraine; CNR, INO, I-50019 Sesto Fiorentino, Italy; European Lab Non Linear Spect, LENS, I-50019 Sesto Fiorentino, Italy; Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy; Ist Italiano Tecnol, Ctr Life Nano Sci Sapienza, 295 Viale Regina Elena, I-00161 Rome, Italy
Abstract: The “Frenkel line” (FL), the thermodynamic locus where the time for a particle to move by its size equals the shortest transverse oscillation period, has been proposed as a boundary between recently discovered liquid-like and gas-like regions in supercritical fluids. We report a simulation study of isothermal supercritical neon in a range of densities intersecting the FL. Specifically, structural properties and single-particle and collective dynamics are scrutinized to unveil the onset of any anomalous behavior at the FL. We find that (i) the pair distribution function smoothly evolves across the FL displaying medium-range order, (ii) low-frequency transverse excitations are observed below the “Frenkel frequency”, and (iii) the high-frequency shear modulus does not vanish even for low-density fluids, indicating that positive sound dispersion characterizing the liquid-like region of the supercritical state is unrelated to transverse dynamics. These facts critically undermine the definition of the FL and its significance for any relevant partition of the supercritical phase.
Journal/Review: THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS
Volume: 8 (20) Pages from: 4995 to: 5001
KeyWords: NONANALYTIC DISPERSION-RELATIONS; GENERALIZED COLLECTIVE MODES; WIDOM LINE; LIQUID-METALS; EXCITATIONS; THERMODYNAMICS; CROSSOVER; STATEDOI: 10.1021/acs.jpclett.7b02176Citations: 29data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2021-10-24References taken from IsiWeb of Knowledge: (subscribers only)Connecting to view paper tab on IsiWeb: Click hereConnecting to view citations from IsiWeb: Click here