Resistance saturation in semi-conducting polyacetylene molecular wires

Area of Science:

• Nanoscience
• Condensed Matter Physics
• Molecular Electronics

Background:

• Understanding nanoscale transport is crucial for molecular electronic devices.
• Semi-conducting trans-polyacetylene molecular wires are modeled using the Su-Schrieffer-Heeger model.
• Charge carriers are endowed with a finite lifetime to simulate realistic conditions.

Purpose of the Study:

• To compare the Landauer and Kubo linear-response formalisms for charge transport.
• To analyze charge transport characteristics in gapped mesoscopic systems.
• To compare these characteristics with those of bulk semiconductors.

Main Methods:

• Utilizing a simplified Su-Schrieffer-Heeger model for trans-polyacetylene molecular wires.
• Numerical and analytical comparisons of Landauer and Kubo formalisms.
• Investigating charge transport in systems with finite charge carrier lifetime.

Main Results:

• Both Landauer and Kubo formalisms predict residual differential conductance at low temperatures for polyacetylene chains.
• Quantitative agreement between the two methods is observed for shorter molecules.
• Landauer transmission decays exponentially with system size, while Kubo response decays hyperbolically.

Conclusions:

• The study highlights differences in transport methodology predictions for molecular devices.
• Findings inform the selection of appropriate theoretical approaches for ab initio modeling.
• The results offer insights into charge transport in gapped mesoscopic systems compared to bulk semiconductors.