Physical Chemistry

Reversed Conductance Decay of 1D Topological Insulators by Tight-Binding Analysis



Reversed conductance decay describes increasing conductance of a molecular chain series with increasing chain length. Realizing reversed conductance decay is an important step towards making long and highly conducting molecular wires. Recent work has shown that one-dimensional topological insulators (1D TIs) can exhibit reversed conductance decay due to their non-trivial edge states. The Su-Schrieffer-Heeger (SSH) model for 1D TIs relates to the electronic structure of these isolated molecules but not their electron transport properties as single-molecule junctions. Herein, we use a tight-binding approach to demonstrate that polyacetylene and other diradicaloid 1D TIs show a reversed conductance decay at the short chain limit. We explain these conductance trends by analyzing the impact of the edge states in these 1D systems on the single-molecule junction transmission. Additionally, we discuss how the self-energy from the electrode-molecule coupling and the on-site energy of the edge sites can be tuned to create longer wires with reversed conductance decays.

Version notes

For equation (8) and (9), we realize that symmetric and antisymmetric combination should depend on the parity of m. Therefore, a (-1)^m coefficient is added.


Thumbnail image of Li_Tight-Binding_1DTI_submitted.pdf

Supplementary material

Thumbnail image of Li_Tight-Binding_SI_Submitted.pdf
Supporting Information for Reversed Conductance Decay of 1D Topological Insulators by Tight-Binding Analysis
1. Su-Schrieffer-Heeger Model 2. Calculating T(E) and T(EF) 3. Quantum Interference in 1D Topological Chain 4. Transmission through Polyacetylene System 5. Transmission through X-Terminated Polyacetylene System 6. Transmission through X-Terminated Polyacetylene System 7. Additional Figures 8. Sample Mathematica Code 9. Reference