  Low-temperature scanning tunneling microscopy is used here to study dynamic
bonding of gold atoms on surfaces under low coordination conditions. In the
experiments, using an atomically-sharp gold tip, a gold adatom is deposited
onto a gold surface with atomic precision either on the first hollow site near
a step edge, or far away from it. Classical molecular dynamics simulations at
4.2 K and density functional theory calculations serve to elucidate the
difference in the bonding behavior between these two different placements,
while also providing information on the crystalline classification of the STM
tips based on their experimental performance.
