title: Density Functional Theory for Steady-State Nonequilibrium Molecular Junctions.
abstract: We present a density functional theory (DFT) for steady-state nonequilibrium quantum systems such as molecular junctions under a finite bias. Based on the steady-state nonequilibrium statistics that maps nonequilibrium to an effective equilibrium, we show that ground-state DFT (GS-DFT) is not applicable in this case and two densities, the total electron density and the density of current-carrying electrons, are needed to uniquely determine the properties of the corresponding nonequilibrium system. A self-consistent mean-field approach based on two densities is then derived. The theory is implemented into SIESTA computational package and applied to study nonequilibrium electronic/transport properties of a realistic carbon-nanotube (CNT)/Benzene junction. Results obtained from our steady-state DFT (SS-DFT) are compared with those of conventional GS-DFT based transport calculations. We show that SS-DFT yields energetically more stable nonequilibrium steady state, predicts significantly lower electric current, and is able to produce correct electronic structures in local equilibrium under a limiting case.
authors.affiliation: Department of Physics and Graphene Research Centre, National University of Singapore, 2 Science Drive 3, Singapore, 117542.
authors.forename: Shuanglong
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Physics and Graphene Research Centre, National University of Singapore, 2 Science Drive 3, Singapore, 117542.
authors.forename: Argo
authors.initials: A
authors.lastname: Nurbawono
authors.affiliation: Department of Physics and Graphene Research Centre, National University of Singapore, 2 Science Drive 3, Singapore, 117542.|Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543.
authors.forename: Chun
authors.initials: C
authors.lastname: Zhang