An exact ab initio theory of quantum transport using TDDFT and nonequilibrium Green's functions

We present an exact ab initio theory for describing the motion of interacting electrons through nanoscopic constrictions. Our theory is based on time-dependent density functional theory (TDDFT) and nonequilibrium Green functions. We consider the system electrode-device-electrode initially contacted and in equilibrium, therefore the scheme is thermodynamically consistent. Besides the steady-state responses one can also calculate physical dynamical responses. We show that the steady-state current results from a dephasing mechanism provided the electrodes are macroscopic and the device is finite. In the d.c. case, we obtain a Landauer-like formula when the effective potential of TDDFT is uniform deep inside the electrodes