Simple Model for Energy and Force Characteristics of Metallic Nanocontacts

TL;DR

This paper models the energy and force oscillations in metallic nanocontacts, specifically gold, using a simple free-electron approach to explain quantum size effects and contact influences.

Contribution

It introduces a straightforward relation between Fermi energy and potential well depth, and analyzes contact effects on force oscillations in metallic nanostructures.

Findings

Force oscillation amplitudes match experimental observations qualitatively

Contact acts as an electron pump affecting electron distribution

Quantum size effects influence energetic and mechanical properties

Abstract

The quantum size oscillations of the energetic properties and the elongation force of the gold slabs and wires, isolated and in a contact with electrodes, are calculated in a free-electron model. A simple relation between the Fermi energy and the square-potential-well depth is used and tested for low-dimensional systems. It is shown that considering the electron subsystem of a slab (or wire) in a contact as open one, the contact acts like a sort of electron pump which sucks or pumps out electrons from the sample. The effect of the contact potential difference on the elastic force oscillations is considered. The calculated amplitudes of force oscillations are in a qualitative agreement with those observed experimentally.