Asymmetric molecular diode energy calculation using Extended Hückel and Parametric method

The Electrical rectification properties of an asymmetric molecule's amine group and nitro group has been studied by placing the compound between two gold electrodes and using Extended Hückel, Parametric and non-equilibrium Green's function (NEGF) formalisms. The conductance of the device falls exponentially with an increased number of $\mathrm{CH}_2$ moieties in the molecule. Current rectification was observed based on HOMO, LUMO gaps and potential drop across the molecules. The investigation of the spatial dispersion of frontier orbitals, the highest occupied molecular orbitals, lowest unoccupied molecular (HOMO-LUMO) of the molecule command the transmission of electrons in the molecule. The results demonstrate that, depending on the group of molecules and number of $\mathrm{CH}_2$ moieties present, current shipping from left side of device to right side of device based on orbital energy gaps. Our findings demonstrate that a true molecular diode can be created, and thus miniaturize the electronic circuit's size to the Nano scale.