Electronic resonance states in metallic nanowires during the breaking process simulated with the ultimate jellium model

TL;DR

This study models the electronic resonance states in metallic nanowires during elongation and breaking using the ultimate jellium model, revealing quantum stabilization effects and conductance oscillations.

Contribution

It introduces a self-consistent density-functional approach with shape restrictions to analyze nanowire stability, conductance, and electronic structures during breaking.

Findings

Quantum shell-structure stabilizes cylindrical nanowires at certain radii.

Conductance oscillates during elongation, correlating with electronic structure changes.

Two electronic configurations emerge: extended states and localized atom-cluster states.

Abstract

We investigate the elongation and breaking process of metallic nanowires using the ultimate jellium model in self-consistent density-functional calculations of the electron structure. In this model the positive background charge deforms to follow the electron density and the energy minimization determines the shape of the system. However, we restrict the shape of the wires by assuming rotational invariance about the wire axis. First we study the stability of infinite wires and show that the quantum mechanical shell-structure stabilizes the uniform cylindrical geometry at given magic radii. Next, we focus on finite nanowires supported by leads modeled by freezing the shape of a uniform wire outside the constriction volume. We calculate the conductance during the elongation process using the adiabatic approximation and the WKB transmission formula. We also observe the correlated oscillations of the elongation force. In different stages of the elongation process two kinds of electronic structures appear: one with extended states throughout the wire and one with an atom-cluster like unit in the constriction and with well localized states. We discuss the origin of these structures.