Elastic Quantum Transports

Not all electronic properties can be described by the eigen states and eigen energies of the electron. To describe the coherent quantum transport (e.g., crossing a molecule, or a potential barrier), it is necessary to solve the scattering states. With localized basis set, it is popular to use the non-equilibrium Green's function method to solve the quantum transport problem. An alternative, and more direct way is to solve the scattering states, which satisfy the Schrodinger's equation, and at the same time, also has some special incoming wave and outgoing wave boundary conditions.

We have developed method using plane wave basis set to solve the scattering state problem. It uses an auxiiliary periodic boundary condition, thus changes the open boundary problem into a closed boundary problem. We have used such method to study the moleculary switch and the tunneling states between electrodes. We plan to use such method to study the leaking current, graphene devices, and spin transport.

A few examples are given here for the systems studied in this group.

The setup of the calculation, and the use of auxiliary boundary condition at B.

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The transmission coefficient crossing a small molecule by two nanowire electrodes

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This is a molecule specially designed to be switched on and off depending on the perpendicular electric fields.

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These are the shape of the tunneling wave functions between two separated electrodes. The shaps of the wave functions depends sensitively on the morphology of the electride.