On simulation of local fluxes in molecular junctions

We present a pedagogical review of current density simulation in molecular junction models indicating its advantages and deficiencies in analysis of local junction transport characteristics. In particular, we argue that current density is a universal tool which provides more information than traditionally simulated bond currents, especially when discussing inelastic processes. However, current density simulations are sensitive to choice of basis and electronic structure method. We note that discussing local current conservation in junctions one has to account for source term caused by open character of the system and intra-molecular interactions. Our considerations are illustrated with numerical simulations of a benzenedithiol molecular junction.