Dynamical correlations and collective excitations of Yukawa liquids

Abstract

Abstract.In dusty (complex) plasmas, containing mesoscopic charged grains, the grain-grain interaction in many cases can be well described through a Yukawa potential. In this Review we summarize the basics of the computational and theoretical approaches capable of describing many-particle Yukawa systems in the liquid and solid phases and discuss the properties of the dynamical density and current correlation spectra of three-and two-dimensional strongly coupled Yukawa systems, generated by molecular dynamics simulations. We show details of the ω(k) dispersion relations for the collective excitations in these systems, as obtained theoretically following the quasilocalized charge approximation, as well as from the fluctuation spectra created by simulations. The theoretical and simulation results are also compared with those obtained in complex plasma experiments.

Collective excitations of a spherically confined Yukawa plasma

“…the mode number n. While for n = 1 the agreement between simulation and theory is very good, the deviations rapidly increase as we go to n ≥ 2, due to the short wavelength character of these modes. This is qualitatively similar to the situation in a macroscopic Yukawa plasma where the Vlasov (mean field) model for the longitudinal dispersion relation ω(k) in the strongly coupled phase is only adequate for ka 1, where k is the wave number [34]. Here the inclusion of correlation effects via the quasi-localized charge approximation was shown to be essential for a reliable description of the dispersion relation for larger wave numbers.…”

Wave spectra of two-dimensional dusty plasma solids and liquids

“…This discrepancy is a consequence of the neglect of the direct thermal effects in the QLCA, which prompts us to discuss a suitable amendment to this theory, to be described in the following subsection. It is not surprising to find that the result of semi-analytic approximation is essentially the same as QLCA in the long wavelength region (up to around [18,26,35]. However, the semi-analytic approximation breaks down for short wavelength.…”

Fluid approach to evaluate sound velocity in Yukawa systems and complex plasmas

“…The third column lists the values of the reduced sound velocity obtained using the QLCA model in Ref. [29]. The last column contains the values of the reduced sound velocity calculated from the simple fluid approach of this paper using Eq.…”

“…Not surprisingly, the influence of strong coupling has been considered by many researchers, from the theoretical point of view, using different approaches. These include quasi-localized charge approximation (QLCA) [27][28][29][30], generalized hydrodynamics [31,32], local field correction description [33], and "multicomponent kinetic theory" [34]. Molecular dynamics (MD) simulations have also been performed to obtain * Also at Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, Russia wave dispersion relations in strongly coupled Yukawa fluids [35,36].…”