Direct Determination of Dynamic Properties of Coulomb and Yukawa Classical One-Component Plasmas

Abstract

Dynamic characteristics of strongly coupled classical one-component Coulomb and Yukawa plasmas are obtained within the nonperturbative model-free moment approach without any data input from simulations so that the dynamic structure factor (DSF) satisfies the first three nonvanishing sum rules automatically. The DSF, dispersion, decay, sound speed, and other characteristics of the collective modes are determined using exclusively the static structure factor calculated from various theoretical approaches including the hypernetted chain approximation. A good quantitative agreement with molecular dynamics simulation data is achieved. . SCPs and warm dense matter are highly relevant model systems for inertial fusion devices [6]. The common property of SCPs is that the interparticle potential energy dominates over the thermal energy. Many of the above-mentioned systems have been analyzed and their characteristic effects became understood within the framework of a seminal model system, the one-component plasma (OCP) model that considers explicitly only one type of charged species, while the presence and the effects of other charged species are expressed by the interaction potential φðrÞ.SCPs, as many-body dynamical systems, exhibit various collective excitations, of which the properties have been investigated both via theoretical approaches and numerical simulations. Numerical approaches provide direct access to the central quantity of collective effects, the dynamic structure factor (DSF). The most successful theoretical approach capable of describing strongly coupled plasmas, the quasilocalized charge approximation [7], is able to predict [from the static pair distribution function (PDF)] the dispersion relations of the collective modes; however, it cannot predict the lifetime (decay) of the modes and the form of the DSF itself. Here we demonstrate that the method of moments theoretical approach [8] is able to predict the form and structure of the DSF of the OCP, based on static data only, i.e., the PDF or the static structure factor (SSF). As both the PDF and the SSF can be obtained theoretically as well [e.g., within the hypernetted chain (HNC) approximation and its modifications including the bridge function] the present approach provides a purely theoretical access to the full DSF and a full quantitative description of the collective modes, including their decay and other characteristics, without the necessity to use simulation data as input, as it was done in [9,10].The moment approach is nonperturbative, nonparametric, and model free. Thus it is perfectly applicable to a broad class of fluids characterized by response functions like semidegenerate multicomponent Coulomb systems or even simple liquids. Because of the rigorous mathematical background, the method is based on automatic satisfaction of sum rules and other exact relations. An empirical guidance is plugged directly into the intermediate step of theoretical computations, thus closing the approach and permitting us, in addition, to determine the dynamic...

Ab initio path integral Monte Carlo approach to the static and dynamic density response of the uniform electron gas

“…Our new data for S(q, ω) can also be used to benchmark approximate methods for the description of quantum dynamics at finite temperature, such as nonequilibrium Green functions [122][123][124][125] and the method of moments by Tkachenko and co-workers [126][127][128].…”

Onset of transverse (shear) waves in strongly-coupled Yukawa fluids

“…One of the important topics in investigating stronglycoupled systems is related to collective dynamics and collective modes. [20][21][22][23][24][25] It is well known that a dense fluid, not too far from the fluid-solid phase transition, can sustain one longitudinal and two transverse modes. The existence of transverse modes in fluids is a consequence of the fact that its response to high-frequency short-wavelength perturbations is similar to that of a solid body.…”

Ab initio Path Integral Monte Carlo Results for the Dynamic Structure Factor of Correlated Electrons: From the Electron Liquid to Warm Dense Matter

“…[26] for a topical discussion), the construction of novel functionals in DFT [51][52][53] and time-dependent DFT [54], and quantum hydrodynamics [56]. In addition, our data will serve as a valuable benchmark for the development of new methods for the description of the dynamics of warm dense electrons, such as the method of moments by Tkachenko and coworkers [78,[96][97][98] and the recently presented advances in the nonequilibrium Green function method by Kas and Rehr [38,39]. ACKNOWLEDGMENTS T.D.…”