Isomorph invariance and thermodynamics of repulsive dense bi-Yukawa one-component plasmas

Abstract

In numerous realizations of complex plasmas, dust-dust interactions are characterized by two screening lengths and are thus better described by a combination of Yukawa potentials. The present work investigates the static correlations and the thermodynamics of repulsive dense bi-Yukawa fluids based on the fact that such strongly coupled systems exhibit isomorph invariance. The strong virialpotential energy correlations are demonstrated with the aid of molecular dynamics simulations, an accurate analytical expression for the isomorph family of curves is obtained and an empirical expression for the fluid-solid phase-coexistence line is proposed. The isomorph-based empirically modified hypernetted-chain approach, grounded on the ansatz of isomorph invariant bridge functions, is then extended to such systems and the resulting structural properties show an excellent agreement with the results of computer simulations. A simple and accurate closed-form expression is obtained for the excess internal energy of dense bi-Yukawa fluids by capitalizing on the compact parameterization offered by the Rosenfeld-Tarazona decomposition in combination with the Rosenfeld scaling, which opens up the energy route to thermodynamics.

Theoretical Estimate of the Glass Transition Line of Yukawa One-Component Plasmas

“…The equation of state proposed by Rosenfeld and Tarazona, within the framework of an asymptotically-high density expansion for purely repulsive potentials, fits well computer simulation results in the strongly coupled stable liquid portion of the YOCP phase diagram and leads to the reduced excess internal energy expression [ 88 , 89 ]. The -dependent parameters and are given in the respective references, while the coupling parameter at the melting point, , can be conveniently expressed via Equation ( 6 ) [ 54 ]. It should be emphasized that both equations of state are strictly valid only for the stable fluid phase of the YOCP.…”

“…The IET equations were solved with a well-established algorithm [ 52 , 54 , 58 ] that is based on Picard iterations in Fourier space combined (when necessary) with mixing and long-range decomposition techniques to facilitate convergence. The Fourier transforms are computed on a discretized domain extending up to with a real space resolution and a reciprocal space resolution .…”

On the advanced integral equation theory description of dense Yukawa one‐component plasma liquids

“…The IEMHNC approach has exhibited an excellent agreement with computer simulations in recent applications to YOCP systems [36] and dense bi-Yukawa liquids. [37] In particular, a thorough investigation of the IEMHNC accuracy for the YOCP was conducted where the IEMHNC approach was validated against LD, MD, and MC simulation results over the entire dense fluid region. [36] The comparison revealed that the IEMHNC approach possesses remarkable accuracy with predictions of structural properties inside the first coordination cell within 2.0% and of thermodynamic properties within 0.5%.…”

“…The objective is to evaluate the performance of the recently proposed IEMHNC approach that is constructed upon the ansatz of bridge function isomorph invariance. [ 36,37 ] The IEMHNC is a very accurate integral equation theory approach, which produces excellent agreement with computer simulations of dense YOCP and bi‐Yukawa liquids. [ 36,37 ] The absence of adjustable parameters makes it an ideal candidate for time‐consuming computations such as the parametric scans of the phase diagram necessary to obtain equations of state.…”

“…[36,37] The absence of adjustable parameters makes it an ideal candidate for time-consuming computations such as the parametric scans of the phase diagram necessary to obtain equations of state. [37] The comparison is carried out in terms of thermodynamic properties, radial distribution functions, thermodynamic consistency, computational speed, and bridge functions against three advanced established integral equation theory approaches; the VMHNC approach constructed upon the conjecture of bridge function quasi-universality, [38] the mixed RY approach that employs a switching function to interpolate between two fundamental closures, [39] the mixed Ballone-Pastor-Galli-Gazzillo (BPGG) approach that introduces an adjustable parameter to enforce thermodynamic consistency. [40] Possible shortcomings of the IEMHNC bridge function are pinpointed, improvement schemes are proposed, and a physically transparent crossover extension is investigated.…”