  We present an escape rate theory for current-induced chemical reactions. We
use Keldysh nonequilibrium Green's functions to derive a Langevin equation for
the reaction coordinate. Due to the out of equilibrium electronic degrees of
freedom, the friction, noise, and effective temperature in the Langevin
equation depend locally on the reaction coordinate. As an example, we consider
the dissociation of diatomic molecules induced by the electronic current from a
scanning tunnelling microscope tip. In the resonant tunnelling regime, the
molecular dissociation involves two processes which are intricately
interconnected: a modification of the potential energy barrier and heating of
the molecule. The decrease of the molecular barrier (i.e. the current induced
catalytic reduction of the barrier) accompanied by the appearance of the
effective, reaction-coordinate-dependent temperature is an alternative
mechanism for current-induced chemical reactions, which is distinctly different
from the usual paradigm of pumping vibrational degrees of freedom.

Mesoscale and Nanoscale Physics