  Electron transport through a diatomic molecular tunnel junction shows wave
like interference phenomenon. By using Keldysh non-equilibrium Green's function
(NEGF) theory, we have explicitly presented current and differential
conductance calculation for a diatomic molecular and two isolated atoms (two
atoms having zero hybridization between their energy orbital) tunnel junctions.
In case of a diatomic molecular tunnel junction, Green's function propagators
entering into current and differential conductance formula interfere
constructively for a molecular anti-bonding state and destructively for bonding
state. Consequently, conductance through a molecular bonding state is
suppressed, and to conserve current, conductance through anti-bonding state is
enhanced. Therefore, current steps and differential conductance peaks amplitude
show asymmetric correspondence between molecular bonding and anti-bonding
states. Interestingly, for a diatomic molecule, comprising of two atoms of same
energy level, these propagators interfere completely destructively for
molecular bonding state and constructively for molecular anti-bonding state.
Hence under such condition, a single step or a single peak is shown up in
current versus voltage or differential conductance versus voltage studies.
