Quantum Interference in Acyclic Systems: Conductance of Cross-Conjugated Molecules

Abstract

We calculate that significant quantum interference effects can be observed in elastic electron transport through acyclic molecules. Interference features are evident in the transmission characteristics calculated for cross-conjugated molecules; significantly, these effects dominate the experimentally observable conduction range. The unusual transport characteristics of these molecules are highlighted through comparison with linearly conjugated and nonconjugated systems. The cross-conjugated molecules presented here show a large dynamic range in conductance. These findings represent a new motif for electron transfer through molecules that exhibit both very high and very low tunneling conductance states accessible at low bias without nuclear motion. In designing single molecule electronic components, a large dynamic range allows a high on/off ratio, a parameter of fundamental importance for switches, transistors, and sensors.

Omni-conducting and omni-insulating molecules

“…A hint comes from observations on calculated transmission in so-called cross-conjugated systems: 11, 39, 40 a connection across a cross-conjugated junction in model systems leads to strong reduction in transmission 40 at energies that are associated with the eigenvalues of the intervening side chain. 39 Within the graph-theoretical version of the SSP model, 13 this corresponds to a theorem that can be derived straightforwardly from our previous work on composite systems.…”

Electron-phonon scattering from Green's function transport combined with molecular dynamics: Applications to mobility predictions

“…This has primarily been done in order to sample different configurations of, e.g., a molecule in contact with two metallic electrodes [16][17][18][19], metallic point contacts [20,21], and carbon nanotubes [22]. A single study used MD simulations to actually probe the energy dependent EPC [23].…”

Inelastic electron tunneling spectroscopy in molecular junctions showing quantum interference

“…Quantum interference (QI) between different molecular orbital pathways has recently emerged as a new route for controlling electronic transport in molecular devices [1][2][3][4][5][6][7]. This quantum mechanical effect arises from simultaneous and opposite contributions to coherent charge transport of at least two molecular orbitals and induces a strong antiresonance in the energy dependent transmission function at the single molecule scale.…”