Yukawa particles confined in a channel and subject to a periodic potential: ground state and normal modes

TL;DR

This study investigates the ground states and normal modes of 2D Yukawa particles confined in a channel with a periodic potential, revealing tunable configurations, phase transitions, and phonon mode localization with potential applications in material design.

Contribution

The paper introduces a detailed analysis of Yukawa particles in a confined channel with a periodic substrate, highlighting new ground state configurations and tunable phonon spectra.

Findings

Identification of multiple ground state configurations with structural transitions.

Discovery of a critical potential strength for particle alignment in minima.

Observation of mode localization and tunable band gaps in phonon spectra.

Abstract

We consider a classical system of two-dimensional (2D) charged particles, which interact through a repulsive Yukawa potential $exp(-r/\lambda)/r$, confined in a parabolic channel which limits the motion of the particles in the $y$-direction. Along the $x$-direction, the particles are also subject to a periodic potential substrate. The ground state configurations and the normal mode spectra of the system are obtained as function of the periodicity and strength of the periodic potential ($V_0$), and density. An interesting set of tunable ground state configurations are found, with first and second order structural transitions between them. A magic configuration with particles aligned in each minimum of the periodic potential is obtained for V_0 larger than some critical value which has a power law dependence on the density. The phonon spectrum of different configurations were also calculated. A localization of the modes into a small frequency interval is observed for a sufficient strength of the periodic potential. A tunable band-gap is found as a function of $V_0$. This model system can be viewed as a generalization of the Frenkel and Kontorova model.