Bound states of tunneling electrons in molecular wires

TL;DR

This paper investigates the bound states of tunneling electrons in molecular wires, revealing complex spectral structures that influence electron transport mechanisms crucial for molecular electronics.

Contribution

It introduces a formalism accounting for many-electron interactions, showing that the bound state spectrum deviates significantly from single-electron models in molecular wires.

Findings

Bound states form two bands instead of one in molecular wires.

The bands exhibit non-analytical square root dispersion near their intersection.

The spectrum structure impacts electron tunneling mechanisms in molecular systems.

Abstract

We have studied the bound states of the extra electron in a molecular wire, corresponding to the physical situation of the electron tunneling through the wire. Based on formalism of the scattering operator that accounts for many-electron interactions we have shown that the energy spectrum of the bound states of the extra electron in a linear chain of three-dimensional scattering centers substantially deviates for spectrum of independent single-electron states of Bloch electrons in a system described by a single-electron effective potential. In particular, in the case of elemental wire consisting of the centers with one electronic state per center, the number of states in the band can be less than number of centers of the wire. These states form two bands instead of single band and the bands exhibit non-analytical, square root dispersion in the vicinity of the point where both bands come together. These findings are important for developing physically viable theory of electron tunneling in single molecular systems because the structure of spectrum of electron's bound states and its relative position in respect to the Fermi levels of electrodes determine specific mechanisms of electron transport through a molecular wire.