High-frequency response of classical strongly coupled plasmas

Abstract

The dynamic structure factor (DSF) of the Yukawa system is here obtained with highly converged molecular dynamics (MD) over the entire liquid phase. The data provide a rigorous test of theoretical models of ion-acoustic wave-dispersion relations, the intermediate scattering function and the high-frequency response. We compare our MD results with seven diverse models, finding good agreement among those that enforce the three basic sum rules for dispersion properties, although one of the models has previously unreported spurious peaks. The MD simulations reveal that the high-frequency response ∼ ω p of the DSF at intermediate frequencies ω, and p shows non-trivial dependencies on the wavevector q and the plasma parameters κ and Γ. In contrast, among the seven comparison models, the predicted high-frequency response is found to be independent of {q, κ, Γ}. This high-frequency power suggests a useful fitting form. In addition, these results expose limitations of several models and, moreover, suggest that some approaches are difficult or impossible to extend because of the lack of finite moments. We also find the double plasmon resonance peak in our MD simulations that none of the theoretical model predicts.

Molecular dynamics investigation of soliton propagation in a two‐dimensional Yukawa liquid

“…In ref. [62] highprecision molecular dynamics results were used for testing of theoretical models of ion-acoustic wave-dispersion relations and related quantities. Studies at the mesoscopic scale of finite dust particle clusters are probably at the most fundamental level, as the contribution of every individual particle is significant.…”

Description of longitudinal modes in moderately coupled Yukawa systems with the static local field correction

“…The shaded region of the (Ω − q) plane roughly demarcates the frequency-wavenumber combinations for which the asymptotic result [1 + ζZ(ζ)] −1 = −2ζ 2 + 3 becomes inaccurate. The rather satisfactory accuracy of the analytic SLFC dispersion relation within the shaded region cannot be justified theoretically and might be illusory given the large uncertainties in the MD extraction of the real eigenfrequencies at short wavelengths [26,31] owing to the damping-induced broadening of the dynamic structure factor peak as q increases [16,30]. From figure 3, it is also evident that the random phase approximation (RPA) dispersion relation, see Eq.…”

“…In addition, particular attention has been paid to the long wavelength limit and to the acquisition of practical expressions for the sound velocities [22][23][24][25]. The ever-growing availability of exact results from molecular dynamics (MD) simulations has helped to distinguish the inherent limitations, quantify the level of accuracy and determine the different applicability ranges of the aforementioned theoretical methods [10,13,16,23,24,[26][27][28][29][30][31]. Given the large number of available approaches, it is expected that there are strong similarities and differences amongst them.…”

“…Given the large number of available approaches, it is expected that there are strong similarities and differences amongst them. Systematic comparisons, on a theoretical and practical level, have only been recently initiated [30].…”

Self-Consistent Relaxation Theory of Collective Ion Dynamics in Yukawa One-Component Plasmas under Intermediate Screening Regimes

“…This formalism serves as a suitable basis for various theories that are proposed for reproducing collective and single-particle dynamics in liquids such as the generalized hydrodynamics [3], the viscoelastic theory [4,5], the mode-coupling theory [6] and others. Despite an impressive progress in the theoretical interpretation of currently available experimental results related to the collective dynamics in liquids [7][8][9], an appropriate theory is still missing, which could be based solely on an interaction potential and structural characteristics as input parameters [10,11].…”