Time correlation functions and generalized transport coefficients of semiquantum helium

Abstract

The dynamic properties of semiquantum He4 are analyzed at two temperatures above the point of superfluid phase transition. Investigations are carried out in the framework of the dynamic thermal viscous model for low and intermediate values of the wave vector. The “momentum–momentum” and “enthalpy–enthalpy” time correlation functions are evaluated and the partial contributions of the collective excitations to these functions are separated. The recurrent relations for memory kernels are used to calculate the time–space dispersion of the generalized transport coefficients.

Collective Dynamics in Single-Particle Motion for Pure Fluids

“…It was shown that in different k-regions, which correspond to distinct spatial scales, different processes are responsible for leading contributions to F nn (k, t) [or, alternatively, to dynamic structure factor S(k, ω)]. In the recent years the GCM approach has been developed in order to investigate collective dynamics in many-component fluids [13], in magnetic liquids [14,15], in semi-quantum helium [16,17], in dipolar [18,19] and site interacting models of polar [20] fluids.…”

A consistent description of kinetics and hydrodynamics of quantum Bose-systems

“…The main step in this direction has been made when investigating semiquantum helium [25,26]. A considerable success was achieved in papers [33][34][35][36] in which the approach to the consistent description of kinetics and hydrodynamics of classical dense gases and fluids is proposed based on the method of nonequilibrium statistical operator by D.N.Zubarev [37,38].…”

“…We can expect then that the difference of contributions from D h kin h kin (k; z) and D h int h int (k; z) will show itself in the dynamic structure factor of semiquantum Bose system in the region of intermediate values of k, ω [25,26]. In the region of intermediate values of wavevector k and frequency ω, it is necessary to take into account all the transport kernels Σ ph kin (k; z),…”

“…From the structure of the dynamical variableĥ int k (3.3) it can be seen that it corresponds to a potential part of the Fourier-component of the generalized enthalpyĥ k which is introduced in the molecular hydrodynamics [25,26]:…”

“…In papers [25,26], a generalized scheme for theoretical description of dynamic properties of semiquantum helium has been proposed based on the method of nonequilibrium statistical operator. Here the set of equations of generalized hydrodynamics is obtained and the thermal viscous model with kinetic and hydrodynamical collective modes is analyzed in detail.…”