Model of electron tunneling coupled to torsional vibrations: Exact solution and study of performance of approximation methods
Abstract
A two dimensional model for the electron interaction with molecular vibrations in molecular junctions is proposed. Alternatively the model can be applied to tunneling through a cylindrical nano structure.
The transmission function is calculated accurately numerically. The exact results are then compared with various approximations: (1) completely frozen vibrations for very light molecule, (2) Chase approximation for very heavy molecule, and (3) discrete-state-in-continuum model in resonant regime.
The validity of these approximations is discussed in terms of the characteristic Lime stales and coupling strengths. The excitation of the vibrational degree of freedom and the emergence of prominent threshold structures in the strong coupling regime are discussed in more derails.