Balanced electron flow and the hydrogen bridge energy levels in Pt, Au, or Cu nanojunctions.

We determined energy levels of the hydrogen bridge in nanojunctions with platinum, gold, or copper anchors. The nanojunctions were modeled in the balanced gain and loss energy scheme. It was shown that the sufficiently strong electron flow through the nanojunction can lead to the reduction in the number of allowed energy levels in the bridge. Over a certain value of the energy of flow, the number of electronic states decreases from six to four and the states with the highest energy disappear. This effect is related to the P T symmetry breaking of the electronic Hamiltonian of the bridge. Subsequently, for still higher values of energy characterizing the electron flow, the bridge disintegrates if subjected to the influence of the stretching force ( F < 0 ) exerted by its anchors. On the other hand, if the exerted force is the compressive one ( F > 0 ), the stability of the hydrogen bridge is ensured by its anchors, and its electronic energy structure is still characterized by four closely spaced energy levels. [ABSTRACT FROM AUTHOR]