Role of the evanescent states in the elastic quantum transport*

The role of evanescent states is always an issue in electronic transport, especially when the energy of the propagating electron is close to a band structure minimum. In this work, we investigate the effects of exact evanescent states on the calculation of the elastic quantum transport through a molecule connected by two quantum wires, based on the method presented in Ref.\,[1]. An exact treatment of evanescent (decaying) states involves the calculation of the complex band structure of the electrodes with imaginary parts of the k vectors. We have calculated the complex band structure under the plane-wave pseudopotential approach. The exact evanescent states are used in the transport calculations with auxiliary boundary condition as described in Ref.\,[1]. The results are exact numerical solutions of the scattering states under a plane-wave pseudopotential formalism. \newline \newline [1] L.W. Wang, Phys. Rev. B. {\bf 72}, 045417 (2005).