  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.
