Dielectric matrix and plasmon dispersion in strongly coupled electronic bilayer liquids

TL;DR

This paper extends the quantum dielectric matrix formalism to strongly coupled bilayer liquids, analyzing plasmon dispersion and revealing an exchange-correlation induced energy gap in out-of-phase modes.

Contribution

It introduces a quantum bilayer dielectric matrix formalism based on the QLCA and calculates plasmon dispersion using Monte Carlo data, highlighting a novel energy gap.

Findings

Out-of-phase plasmon mode exhibits a long-wavelength energy gap.

The formalism generalizes previous single-layer models to bilayers.

Results agree with classical predictions and recent simulations.

Abstract

We develop a dielectric matrix and analyze plasmon dispersion in strongly coupled charged-particle bilayers in the quantum domain. The formulation is based on the classical quasi-localized charge approximation (QLCA) and extends the QLCA formalism into the quantum domain. Its development, which parallels that of 2D companion paper [Phys. Rev. E 70, 026406 (2004)] by three of the authors, generalizes the single-layer scalar formalism therein to a bilayer matrix formalism. Using pair correlation function data generated from diffusion Monte Carlo simulations, we calculate the dispersion of the in-phase and out-of-phase plasmon modes over a wide range of in-layer coupling values and layer spacings. The out-of-phase spectrum exhibits an exchange-correlation induced long-wavelength energy gap in contrast to earlier predictions of acoustic dispersion softened by exchange-correlations. The energy gap is similar to what has been previously predicted for classical charged-particle bilayers and subsequently confirmed by recent molecular dynamics computer simulations.