Effective bias and potentials in steady-state quantum transport : A NEGF reverse-engineering study

摘要

Using non-equilibrium Green’s functions combined with many-body perturbationtheory, we have calculated steady-state densities and currents through short interacting chainssubject to a finite electric bias. By using a steady-state reverse-engineering procedure, theeffective potential and bias which reproduce such densities and currents in a non-interactingsystem have been determined. The role of the effective bias is characterised with the aid of theso-called exchange-correlation bias, recently introduced in a steady-state density-functionaltheoryformulation for partitioned systems. We find that the effective bias (or, equivalently,the exchange-correlation bias) depends strongly on the interaction strength and the lengthof the central (chain) region. Moreover, it is rather sensitive to the level of many-bodyapproximation used. Our study shows the importance of the effective/exchange-correlationbias out of equilibrium, thereby offering hints on how to improve the description of densityfunctional-theorybased approaches to quantum transport.