Molecular electronics is a promising solution to extend the Moore’s law beyond the quantum limit of silicon-based semiconductors. Most explicit theoretical approaches treat quantum transport in molecular electronics using a combination of density functional theory and nonequilibrium Green's functions. This is a static formalism, with dynamic response properties accommodated only through complicated extensions. To circumvent this limitation, the carrier density may be propagated using real-time time-dependent density functional theory, with boundary conditions corresponding to an open quantum system. Specifically, an asymmetric transmission resonance complex potential is added to the system’s Hamiltonian to mimic electron injection, while a singular polynomial complex potential is used to emulate electron depletion. As shown in a one-dimensional model system, the increased bias voltage greatly facilities the Gaussian wavepacket propagation through a high scattering barrier while the relative conductance is nearly flat for low-resistance transmission. Moreover, the excellent linearity of conductance with respect to barrier height conforms to Ohm’s law for an ideal ballistic resistor. We believe this is a first step toward developing a complete time-dependent quantum transport theory that can be used to study photoconductivity in optical molecular electronics.

Real-time electron transport from parity-time symmetric quantum mechanics

249th National Meeting (2015)

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