Non-equilibrium lifetimes of DNA under electronic current in a molecular junction

Abstract

We investigate the non-equilibrium mechanical motion of double-stranded DNA in a molecular junction under electronic current using Keldysh–Langevin molecular dynamics. Non-equilibrium electronic force reshapes the effective potential energy surface and along with electronic viscosity force and stochastic force, governs voltage-dependent dynamics of DNA’s collective mechanical coordinate. We compute mean first-passage times to quantify the non-equilibrium lifetime of the DNA junction. At low voltage biases, electron–mechanical motion coupling destabilizes DNA by shifting the potential minimum toward critical displacement and suppressing barriers, thus shortening lifetimes by several orders of magnitude. Unexpectedly, at higher voltages, the trend reverses: the potential minimum shifts away from instability and the barrier re-emerges, producing re-stabilization of the junction. In addition, we demonstrate the Landauer blowtorch effect in this system: coordinate-dependent fluctuations generate a spatially varying effective temperature, changing current-induced dynamics of mechanical degrees of freedom. Apparent temperatures of DNA mechanical motion increase far above ambient due to current-induced heating, correlating with suppressed electronic current at stronger couplings. Our results reveal a non-equilibrium interplay between current-driven forces, dissipation, and fluctuations in DNA junctions, establishing mechanisms for both destabilization and recovery of DNA stability under electronic current.