On the estimation of sound speed in two-dimensional Yukawa fluids

Klumov

2018

Physics of Plasmas

An approach to calculate high-frequency bulk and shear modului of two-dimensional (2D) weakly screened Yukawa fluids and solids is presented. Elastic moduli are directly related to sound velocities and other important characteristics of the system. In this article we discuss these relations and present exemplary calculation of the longitudinal, transverse, and instantaneous sound velocities and derive a differential equation for the Einstein frequency. Simple analytical results presented demonstrate good accuracy when compared with numerical calculations. The obtained results can be particularly useful in the context of 2D colloidal and complex (dusty) plasma monolayers.

Section: Resultsmentioning

confidence: 91%

High-frequency elastic moduli of two-dimensional Yukawa fluids and solids

Klumov

2018

Physics of Plasmas

“…This functional form has been proven to be very useful for various fluids characterized by soft long-ranged interactions in 2D. 31,32,88,89 Appendix B: Simplified expressions for L and T The explicit expressions for L(k) and T (k) for the 2D Coulomb system are 21,55 L 2 (k) = ω 2 0 q + ω 2 0 ∞ 0 h(x) 2x 2 [1 − J 0 (qx) + 3J 2 (qx)] dx,…”

Section: Discussionmentioning

confidence: 99%

Collective modes of two-dimensional classical Coulomb fluids

The Journal of Chemical Physics

Kryuchkov

Mistryukova

et al. 2018

Molecular dynamics simulations have been performed to investigate in detail collective modes spectra of twodimensional Coulomb fluids in a wide range of coupling. The obtained dispersion relations are compared with theoretical approaches based on quasi-crystalline approximation (QCA), also known as the quasi-localized charge approximation (QLCA) in the plasma-related context. An overall satisfactory agreement between theory and simulations is documented for the longitudinal mode at moderate coupling and in the longwavelength domain at strong coupling. For the transverse mode, satisfactory agreement in the long-wavelength domain is only reached at very strong coupling, when the cutoff wave-number below which shear waves cannot propagate becomes small. The dependence of the cutoff wave-number for shear waves on the coupling parameter is obtained.

“…For strongly coupled Yukawa systems we have γ 1, which is a general property of soft repulsive interactions. [54][55][56] This fluid approach has been exploited previously for Yukawa systems in 3D case 10,54 as well as in 2D case. 55 Generalization to 1D case is trivial.…”

Section: Sound Velocities In Different Spatial Dimensionsmentioning

confidence: 99%

Unified description of sound velocities in strongly coupled Yukawa systems of different spatial dimensionality

2019

Physics of Plasmas

Sound velocities in classical single-component fluids with Yukawa (screened Coulomb) interactions are systematically evaluated and analyzed in one-, two-, and three spatial dimensions (D = 1, 2, 3). In the strongly coupled regime the convenient sound velocity scale is given by Q 2 /∆m, where Q is the particle charge, m is the particle mass, n is the particle density, and ∆ = n −1/D is the unified interparticle distance. The sound velocity can be expressed as a product of this scaling factor and a dimension-dependent function of the screening parameter, κ = ∆/λ, where λ is the screening length. A unified approach is used to derive explicit expressions for these dimension-dependent functions in the weakly screened regime (κ 3). It is also demonstrated that for stronger screening (κ 3), the effect of spatial dimensionality virtually disappears, the longitudinal sound velocities approach a common asymptote, and a one-dimensional nearest-neighbor approximation provides a relatively good estimate for this asymptote. This result is not specific to the Yukawa potential, but equally applies to other classical systems with steep repulsive interactions. An emerging relation to a popular simple freezing indicator is briefly discussed. Overall, the results can be useful when Yukawa interactions are relevant, in particular, in the context of complex (dusty) plasmas and colloidal suspensions.