2002/09/25 by Stéphane Pleutin, Hermann Grabert, Gert-Ludwig Ingold +1 · 1 citation
Physics and Astronomy · #physics.chem-ph #cond-mat.mes-hall
paper · pdf · doi:10.1063/1.1539863
published as J. Chem. Phys. 118, 3756 (2003) · 8 pages, 5 figures, RevTeX4
arxiv created 2002/09/25 · arxiv updated 2009/11/30
We study the electrostatic potential of a molecular wire bridging two metallic electrodes in the limit of weak contacts. With the use of a tight-binding model including a fully three-dimensional treatment of the electrostatics of the molecular junction, the potential is shown to be poorly screened, dropping mostly along the entire molecule. In addition, we observe pronounced Friedel oscillations that can be related to the breaking of electron-hole symmetry. Our results are in semi-quantitative agreement with recent state-of-the-art ab initio calculations and point to the need of a three-dimensional treatment to properly capture the behavior of the electrostatic potential. Based on these results, current-voltage curves are calculated within the Landauer formalism. It is shown that Coulomb interaction partially compensates the localization of the charges induced by the electric field and consequently tends to suppress zones of negative differential resistance.