  The interaction between electronic and nuclear degrees of freedom in
single-molecule junctions is an essential mechanism, which may result in the
current-induced rupture of chemical bonds. As such, it is fundamental for the
stability of molecular junctions and for the applicability of molecular
electronic devices. In this publication, we study current-induced bond rupture
in molecular junctions using a numerically exact scheme, which is based on the
hierarchical quantum master equation (HQME) method in combination with a
discrete variable representation for the nuclear degrees of freedom. Employing
generic models for molecular junctions with dissociative nuclear potentials, we
identify distinct mechanisms leading to dissociation, namely the electronic
population of anti-bonding electronic states and the current-induced heating of
vibrational modes. Our results reveal that the latter plays a negligible role
whenever the electronic population of anti-bonding states is energetically
possible. Consequently, the significance of current-induced heating as a source
for dissociation in molecular junctions involving an active anti-bonding state
is restricted to the non-resonant transport regime, which reframes the
predominant paradigm in the field of molecular electronics.
