Correlation effects in molecular conductors

Abstract

The source-sink potential (SSP) model introduced previously [F. Goyer, M. Ernzerhof, and M. Zhuang, J. Chem. Phys. 126, 144104 (2007)] enables one to eliminate the semi-infinite contacts in molecular electronic devices (MEDs) in favor of complex potentials. SSP has originally been derived for independent electrons and extended to interacting two-electron systems subsequently [A. Goker, F. Goyer, and M. Ernzerhof, J. Chem. Phys. 129, 194901 (2008)]. Here we generalize SSP to N-electron systems and consider the impact of electron correlation on the transmission probability. In our correlated method for molecular conductors, the molecular part of the Hückel Hamiltonian of the original SSP is replaced by the Hubbard Hamiltonian. For the contacts, however, the single-electron picture is retained and they are assumed to be spin polarized. Using our method, we study electron transmission in molecular wires, cross-conjugated chains, as well as aromatic systems. We find that, for realistic values of the electron-electron repulsion parameter, correlation effects modify the transmission probability quantitatively, the qualitative features remain. However, we find subtle new effects in correlated MEDs, such as Coulomb drag, that are absent in uncorrelated systems.