Electron wind force in an atomistic non-equilibrium molecular dynamics simulation

We demonstrate electronic friction on metals by addressing the reverse process – the force imparted on the atoms by the flow of an electronic current in the metal. By well established Ehrenfest dynamics we implement a quantum-classical simulation of the motion of a chain of classical atoms forming a contactless monatomic ring, where electrons flow by nearest neighbor hopping between atomic-like orbitals in an electric field generated by a linearly growing external magnetic field threading the ring. In the real time dynamics, electron-phonon scattering events take the form of Landau-Zener processes, each of them imparting momentum to the classical atoms, that can vibrate and also dissipate to a bath. The realistic features of electron conduction and resistivity are recovered in this model, plus a microscopic description of the current-induced momentum transfer to the atoms which vibrate and to the whole chain which drifts. When one additional adatom is added to the chain, the quantum mechanics of the wind force and the resulting electromigration drift are controlled by the weak hybridization of the adatom orbital to the chain atomic orbitals where the current flows, suggestive of a rather general mechanism.