Ab initio investigation on electron transfer in molecular electronic devices: A minimal model study

The electron transfer of a model system, Au-benzene-1,4-dithiolate-Au, in the presence of an external electric field is investigated. Both the cis- and trans-conformations are considered. The calculations show that, for both conformations, the interatomic distance between gold and sulfur on the site with an extra localized electron is shortened by about 0.17 Å when the extra electron transfers to the other site. On the other hand, the reorganization energies of both conformations are almost the same, about 29 kJ mol−1. The electron transfer coupling matrix elements are 0.42 and 0.73 kJ mol−1, while the threshold field strengths are 8.5 × 10−4 and 7.4 × 10−4 a.u. for the cis- and trans-conformations, respectively.