The first-principle study of single molecular switch based on Hydrogen Tautomerization sandwiched between atomic chain electrode

Using DFT based NEGF technique, we investigated electrical transport properties of the single-molecular switch, phthalocyanine (H2Pc), based on hydrogen tautomerization. The molecule is coupled to 1-D electrodes in the form of semi- infinite metallic chains of gold and carbon. Hydrogen tautomerization affects the electronic state of H2Pc by switching the alignment of the molecular orbital energies between HOMO and HOMO-1, and causes a substantial change in the tunnelling current. As a consequence switching can be achieved already in the low-bias regime for both electrode models. For gold chain electrode, molecule-metal interaction at the junction leads to modification of the electronic structure of H2Pc, and hence multi-peak NDR is obtained. It is revealed that the even-numbered Au atoms provide stronger NDR than odd- numbered Au atom. Owing to interesting switching characteristics of H2Pc based on hydrogen tautomerization, it could potentially function as a molecular switch in nano electronic circuits.