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

• Published in: Journal of physics. Conference series Vol. 696; no. 1; pp. 12018 - 12029
• Main Authors: Karlsson, Daniel, Verdozzi, Claudio
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 12.04.2016
• Subjects: Bias; Chains; Condensed Matter Physics; Condensed Matter Physics (including Material Physics, Nano Physics); Den kondenserade materiens fysik; Den kondenserade materiens fysik (Här ingår: Materialfysik, nanofysik); Density; Exchanging; Fysik; Green's functions; Mathematical analysis; Natural Sciences; Naturvetenskap; Perturbation theory; Physical Sciences; Physics; Quantum transport; Steady state; System effectiveness
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/696/1/012018

Using non-equilibrium Green's functions combined with many-body perturbation theory, we have calculated steady-state densities and currents through short interacting chains subject to a finite electric bias. By using a steady-state reverse-engineering procedure, the effective potential and bias which reproduce such densities and currents in a non-interacting system have been determined. The role of the effective bias is characterised with the aid of the so-called exchange-correlation bias, recently introduced in a steady-state density-functional- theory formulation for partitioned systems. We find that the effective bias (or, equivalently, the exchange-correlation bias) depends strongly on the interaction strength and the length of the central (chain) region. Moreover, it is rather sensitive to the level of many-body approximation used. Our study shows the importance of the effective exchange-correlation bias out of equilibrium, thereby offering hints on how to improve the description of density- functional-theory based approaches to quantum transport.