Real-Space Description of Dynamics of Liquids

Abstract

In strongly disordered matter, such as liquids and glasses, atomic and magnetic excitations are heavily damped and partially localized by disorder. Thus, the conventional descriptions in terms of phonons and magnons are inadequate, and we have to consider spatially correlated atomic and spin dynamics in real-space and time. Experimentally this means that the usual representation of dynamics in terms of the dynamic structure factor, S(Q, E), where Q and E are the momentum and energy exchanges in scattering, is insufficient. We propose a real-space description in terms of the dynamic pair-density function (DyPDF) and the Van Hove function (VHF) as an alternative, and discuss recent results on superfluid 4He by inelastic neutron scattering and water by inelastic X-ray scattering. Today much of the objects of research in condensed-matter physics and materials science are highly complex materials. To characterize the dynamics of such complex materials, the real-space approach is likely to become the mainstream method of research.

Structural Changes in Metallic Glass-Forming Liquids on Cooling and Subsequent Vitrification in Relationship with Their Properties

“…As well as crystals liquids retain their volume but flow under gravity [ 68 , 69 ]. Owing to thermal excitations their local atomic structure constantly undergoes some changes even at a constant temperature [ 70 , 71 ]. Equilibrium metallic melts show nearly Arrhenius-type temperature dependence of the dynamic viscosity ( η ): η = η 0 exp(E a /RT) where η 0 is a pre-exponential factor, here R is the gas constant (please note that it is different from the radial distance defined above) and E a is an activation energy for viscous flow (some values are listed in Refs.…”

Kuramoto synchronization of quantum tunneling polarons for describing the dynamic structure in cuprate superconductors

“…IQTPs are a contributor to the dynamic structure, S(Q, E). This quantity is easily intuited in liquids, where the positions of atoms in rapid transit between quasi-stable relative locations are identified in the van Hove function derived from inelastic scattering data [5]. X-ray Absorption Fine Structure (XAFS) spectroscopy obtains this dynamic structure via its sensitivity to the instantaneous structure factor, S(k, t = 0) [6,7].…”

An atomistic study of the structural changes in a Zr–Cu–Ni–Al glass-forming liquid on vitrification monitored in-situ by X-ray diffraction and molecular dynamics simulation

“…Liquids retain their volume as crystals but flow under the action of gravity [ 8 , 9 ]. They constantly undergo a restructuring of the atomic structure [10,11]. Above the equilibrium liquidus temperature (Tl) and slightly below it metallic melts show nearly Arrhenius-type temperature dependence of viscosity ():…”