A fundamental numerical and theoretical study for the vibrational properties of nanowires

TL;DR

This study combines molecular dynamics simulations and classical beam theory to analyze the vibrational properties of silver nanowires, revealing effects of excitation, temperature, and nonlinear dynamics on their vibrational behavior.

Contribution

It introduces a comprehensive analysis of nanowire vibrations using MD simulations and classical theory, highlighting nonlinear effects and multi-mode excitation strategies.

Findings

Q-factor decreases with higher initial excitation amplitude

Moderate plastic deformation increases the first natural frequency

First natural frequency decreases with temperature

Abstract

Based on the molecular dynamics (MD) simulation and the classical Euler-Bernoulli beam theory, a fundamental study of the vibrational performance of the Ag nanowire (NW) is carried out. A comprehensive analysis of the quality (Q)-factor, natural frequency, beat vibration, as well as high vibration mode is presented. Two excitation approaches, i.e., velocity excitation and displacement excitation, have been successfully implemented to achieve the vibration of NWs. Upon these two kinds of excitations, consistent results are obtained, i.e., the increase of the initial excitation amplitude will lead to a decrease to the Q-factor, and moderate plastic deformation could increase the first natural frequency. Meanwhile, the beat vibration driven by a single relative large excitation or two uniform excitations in both two lateral directions is observed. It is concluded that the nonlinear changing trend of external energy magnitude does not necessary mean a non-constant Q-factor. In particular, the first order natural frequency of the Ag NW is observed to decrease with the increase of temperature. Furthermore, comparing with the predictions by Euler-Bernoulli beam theory, the MD simulation provides a larger and smaller first vibration frequency for the clamped-clamped and clamped-free thin Ag NWs, respectively. Additionally, for thin NWs, the first order natural frequency exhibits a parabolic relationship with the excitation magnitudes. The frequencies of the higher vibration modes tend to be low in comparison to Euler-Bernoulli beam theory predictions. A combined initial excitation is proposed which is capable to drive the NW under a multi-modes vibration and arrows the coexistence of all the following low vibration modes. This work sheds lights on the better understanding of the mechanical properties of NWs, and benefits the increasing utilities of NWs in diverse nano-electronic devices.