Spin-polarized electron transport in a molecular wire: tuning the conductivity through conformational changes

We investigate theoretically the electrical conductivity of a molecular wire consisting of three linked benzene molecules. By using magnetic electrodes the conductivity becomes spin-dependent, the degree of this dependence varying with the relative spin-alignment of the two electrodes. Of particular interest is how the the conductivity depends on the geometrical conformation of the benzene wire. Here we use density-functional theory and the Landauer-B\"{u}ttiker method to calculate this dependence from first principles. We find that the current depends sensitively on the conformation, with a near-planar configuration of the three benzene rings giving significantly higher current (by $\sim$30\%) than the ground-state non-planar structure.