# Directional bonding explains high conductance values of atomic contacts in bcc metals

## TL;DR

This paper demonstrates that directional bonding in bcc metals leads to highly coordinated stable atomic contacts with high conductance, explaining experimental observations that contradict traditional expectations.

## Contribution

It introduces a classical molecular dynamics approach with directional bonding potentials to explain high conductance in bcc metal contacts, highlighting the importance of bonding directionality.

## Key findings

- Highly coordinated structures form before rupture due to directional bonding.
- Conductance calculations match experimental measurements for bcc metals.
- Directional bonding significantly influences atomic contact stability and conductance.

## Abstract

Atomic-sized junctions of iron, created by controlled rupture, present unusually high values of conductance compared to other metals. This result is counter-intuitive since, at the nanoscale, body-centered cubic metals are expected to exhibit lower coordination than face-centered cubic metals. In this work, classical molecular dynamics simulations of contact rupture, using an interatomic potential that accounts for directional bonding, yield highly-coordinated stable structures before rupture, unlike an isotropic bonding potential, which results in the expected stable single-atom contacts. Density functional theory electronic transport calculations show that conductance values of these highly coordinated and highly stable structures, can explain the experimentally measured values for conductance of body-centered cubic atomic contacts, thus revealing the important role of directional bonding in these metals.