Inelastic effects in molecular transport junctions: The probe technique at high bias

Abstract

We extend the Landauer-Büttiker probe formalism for conductances to the high bias regime, and study the effects of environmentally-induced elastic and inelastic scattering on charge current in single molecule junctions, focusing on high-bias effects. The probe technique phenomenologically incorporates incoherent elastic and inelastic effects to the fully coherent case, mimicking a rich physical environment at trivial cost. We further identify environmentally-induced mechanisms which generate an asymmetry in the current, manifested as a weak diode behavior. This rectifying behavior, found in two types of molecular junction models, is absent in the coherent-elastic limit, and is only active in the case with incoherent-inelastic scattering. Our work illustrates that in the low bias -linear response regime, the commonly used "dephasing probe" (mimicking only elastic decoherence effects) operates nearly indistinguishably from a "voltage probe" (admitting inelasticdissipative effects). However, these probes realize fundamentally distinct I-V characteristics at high biases, reflecting the central roles of dissipation and inelastic scattering processes on molecular electronic transport far-from-equilibrium.

From Exhaustive Simulations to Key Principles in DNA Nanoelectronics

“…Here, we use an alternative, low-cost technique and account for system-environment interactions by employing the Landauer-Büttiker probe method [27,28]. It is applicable for the study of charge conduction in a wide range of systems, from single-atom point contacts up to the thermodynamic limit [19,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]65]. In this technique, incoherent elastic and inelastic electron (or hole) scattering effects are taken into account by augmenting the non-interacting electronic Hamiltonian with probe terminals through which charge carriers loose their phase memory and possibly exchange energy with other degrees of freedom.…”

Controlling charge transport mechanisms in molecular junctions: Distilling thermally induced hopping from coherent-resonant conduction

“…In Refs. 41,42 , we further used the LBP technique to simulate high-bias voltage effects, specifically, the role of environmental interactions on the operation of a molecular junction as a diode.…”

Thermopower of molecular junctions: Tunneling to hopping crossover in DNA

“…In Refs. 58,59 , we further used the LBP technique to simulate high-bias voltage effects, specifically the role of environmental interactions on the diode operation. More recently, we demonstrated that the LBP method can uncover an intermediate quantum coherent-incoherent transport regime in DNA junctions 60 .…”