At low bias voltage and in its HOMO-LUMO energy gap interval, the conductance of a molecular wire decays exponentially while increasing its length. The same phenomenon occurs with a surface dangling bond atomic wire. The corresponding inverse decay length beta of this through bond tunneling phenomenon ranges for example from beta = 1.2 A^-1 for an alkane molecular wire to about beta = 0.2 A^-1 for a medium large HOMO-LUMO gap kappa conjugated molecular wire. As a function of kappa and of the effective mass m* of the tunneling electrons, beta varies following a universal monotonic decay law. For a given kappa we will discuss (1) what prevents beta to be exactly zero that is reaching what can be named a super tunneling transport regime, (2) how to approach a minimum beta value by a good choice of the chemical composition of the molecular wire.
At low bias voltage and in its HOMO-LUMO energy gap interval, the conductance of a molecular wire decays exponentially while increasing its length. The same phenomenon occurs with a surface dangling bond atomic wire. The corresponding inverse decay length beta of this through bond tunneling phenomenon ranges for example from beta = 1.2 A^-1 for an alkane molecular wire to about beta = 0.2 A^-1 for a medium large HOMO-LUMO gap kappa conjugated molecular wire. As a function of kappa and of the effective mass m* of the tunneling electrons, beta varies following a universal monotonic decay law. For a given kappa we will discuss (1) what prevents beta to be exactly zero that is reaching what can be named a super tunneling transport regime, (2) how to approach a minimum beta value by a good choice of the chemical composition of the molecular wire.
