Excitation of vibrational soft modes in disordered systems using active oscillation

TL;DR

This paper introduces a computationally efficient method to analyze vibrational modes in disordered solids by actively oscillating particles and measuring their real-time displacements, revealing detailed vibrational characteristics.

Contribution

The authors develop a novel active oscillation technique that correlates real-time particle displacements with normal mode analysis, enabling large-scale vibrational studies with lower computational costs.

Findings

Identified three frequency regimes with distinct vibrational spatial distributions.

Demonstrated strong correlation between active oscillation responses and normal mode eigenvectors.

Proposed application of the method to larger systems for detailed low-frequency vibrational analysis.

Abstract

We propose a new method to characterize the spatial distribution of particles' vibrations in solids with much lower computational costs compared to the usual normal mode analysis. We excite the specific vibrational mode in a two dimensional athermal jammed system by giving a small amplitude of active oscillation to each particle's size with an identical driving frequency. The response is then obtained as the real time displacements of the particles. We show remarkable correlations between the real time displacements and the eigen vectors obtained from conventional normal mode analysis. More importantly, from these real time displacements, we can measure the participation ratio and spatial polarization of particles' vibrations. From these measurements, we find three distinct frequency regimes which characterize the spatial distribution and correlation of particles' vibrations in jammed amorphous solids. Furthermore, we can possibly apply this method to a much larger system to examine the low frequency behaviour of amorphous solids with a much higher resolution of the frequency space.