Asymmetric electron bilayer: A molecular dynamics study of correlations and diffusion

Abstract

Molecular dynamics simulations of a classical asymmetric electron bilayer for various values of the interlayer separation distance $d$ and various degrees of asymmetry have been performed. The number of charged particles in the basic cell of one layer was fixed at 512, corresponding to a coupling strength $\ensuremath{\Gamma}(=\frac{{e}^{2}}{a{k}_{B}T})$ of 80, while that of the other varied from 32 to 512 particles, corresponding to a $\ensuremath{\Gamma}$ of 20 to 80; $a$ is the Wigner-Seitz radius. We have analyzed the intralayer and interlayer pair-correlation functions and the self-diffusion coefficients of the two layers and compared them with those of a symmetric electron bilayer. It is found that the self-diffusion coefficients of the two layers do not differ significantly for values of $d\ensuremath{\le}0.8$ with a marked deviation setting for $d=2$. A fluid-solid phase transition, observed previously for the symmetric bilayer for certain values of $d$, no longer exists even for the slightly asymmetric (512,450) bilayer we considered.