Nonadiabatic corrections to electric current in molecular junction due to nuclear motion at the molecule-electrode interfaces

TL;DR

This paper develops a quantum transport theory incorporating nuclear motion effects at molecule-electrode interfaces, revealing how atomic dynamics influence electric current in molecular junctions.

Contribution

It introduces a non-adiabatic correction framework using non-equilibrium Green's functions that accounts for nuclear velocities and accelerations in electron transport calculations.

Findings

Nuclear motion significantly affects molecular junction conductivity.

Second-order derivatives improve the accuracy of current predictions.

The theory provides a basis for more realistic modeling of molecular electronics.

Abstract

We present quantum electron transport theory that incorporates dynamical effects of motion of atoms on electrode-molecule interfaces in the calculations of the electric current. The theory is based on non-equilibrium Green's functions. We separate time scales in the Green's functions on fast relative time and slow central time. The derivative with respect to the central time serves as a small parameter in the theory. We solve the real-time Kadanoff-Baym equations for molecular Green's functions using Wigner representation and keep terms up to the second order with respect to the central time derivatives. Molecular Green's functions and consequently the electric current are expressed as functions of molecular junction coordinates as well as velocities and accelerations of molecule-electrode interface nuclei. We apply the theory to model a molecular system and study the effects of non-adiabatic nuclear motion on molecular junction conductivity.