Molecular dynamics simulation of Cu deposition near a step on the Cu(001) surface showing steering effect (attraction to top layer of step)
Atom landing 'between' of step atoms:
(click reload to restart)
Notice how the depositing atom "slides in" between the two step-edge atoms after bouncing and is then attracted to the top terrace. This gives rise to a positive surface current (instability).
The depositing atom is initially close to the critical distance y = 0.3 b beyond the edge of the step, corresponding to attraction to the top terrace but is now 'between' of the neighboring step atoms.
(Atom initial kinetic energy = 0.1 eV, substrate temperature = 84 K)