Risultati scientifici

Collective Excitations in Supercritical Fluids

Anno: 2015

Autori: Bryk T., Gorelli F., Ruocco G., Santoro M., Scopignio T.

Affiliazione autori: Natl Acad Sci Ukraine, Inst Condensed Matter Phys, UA-79011 Lvov, Ukraine; CNR INO, Ist Nazl Ott, I-50019 Sesto Fiorentino, Italy;‎ LENS, I-50019 Sesto Fiorentino, Italy;‎ Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy;‎ Ist Italiano Tecnol, Ctr Life Nano Sci Sapienza, I-00161 Rome, Italy

Abstract: Recent progress in theoretical and simulation studies of collective excitations in supercritical fluids is reviewed. We discuss a methodology of fit-free estimation of dispersion of longitudinal and transverse excitations in simple fluids. The issue of vanishing positive sound dispersion-a viscoelastic increase of the speed of sound from adiabatic one to its high-frequency (elastic) value-with reduction of density, as it was observed in inelastic X-ray scattering experiments on supercritical Ar, is discussed from the point of view of finding distinctions in collective dynamics of low-and high-density supercritical fluids. On the basis of several theoretical models within the extended hydrodynamic description of density-density correlations in liquids analytical expressions for positive sound dispersion are obtained and applied for analysis of time correlation functions obtained from molecular dynamics simulations. A location of a crossover from the liquid-like to gas-like types of collective dynamics is discussed based on general findings for spectra of collective excitations in supercritical Ar and soft sphere fluids.

Titolo Convegno:
Luogo:

Parole chiavi: WAVELENGTH SOUND MODES; BINARY-LIQUIDS; THERMAL-DIFFUSIVITY; DYNAMICS; ARGON; FLUCTUATION; DEPENDENCE; METALS; LINE

gdpr-image
This site uses cookies. If you decide to continue browsing we consider that you accept their use. For more information about cookies and how to delete them please read our Info Policy on cookies use.
Read more