Quantum interference: The structural dependence of electron transmission through model systems and cross-conjugated molecules

We report on a class of molecules that exhibit nonlinear current/voltage behavior in the low bias tunneling regime. This interesting behavior is attributed to quantum interference. Using site models, we show that interference features, while common, do not necessarily occur at experimentally relevant energies, hindering realization in transport measurements. Calculations made using a nonequilibrium Green's function code show that quantum interference can be experimentally relevant in cross-conjugated molecules. A detailed bond length analysis of cross-conjugated molecules gives insight into why these molecules have interference at energetically accessible regions. The interference features are shown to be stable to both an electronic dephasing analysis and geometric fluctuations provided by molecular dynamics.