Topological Advantage for Adsorbate Chemisorption on Conjugated Chains

Area of Science:

• Condensed Matter Physics
• Quantum Chemistry
• Materials Science

Background:

• Topological matter offers novel ways to control charge and energy flow.
• Its implications for chemistry, particularly molecular interactions, are not fully understood.
• The Su-Schrieffer-Heeger (SSH) model provides a framework for studying topological phases in polyacetylene chains.

Purpose of the Study:

• Investigate how different electronic phases of an SSH chain affect molecular adsorbates.
• Quantify charge donation and electronic friction of adsorbates coupled to trivial insulators, metals, and topological insulators.
• Explore the role of localized states at edges and solitons in these interactions.

Main Methods:

• Simulated an ensemble of adsorbates with an empty lowest unoccupied molecular orbital (LUMO).
• Coupled adsorbates to various sites (edges, solitons, bulk) of an SSH polyacetylene chain.
• Analyzed charge donation into the LUMO and adsorbate electronic friction across different topological phases.

Main Results:

• Charge donation and electronic friction are significantly impacted by the SSH chain's electronic phase.
• Localized midgap states at edges and solitons strongly enhance electron donation compared to metallic and trivial phases.
• Electronic friction is highest in the metallic phase, suppressed in gapped regions, and intermediate at topological edges.

Conclusions:

• The electronic phase of topological matter, particularly the presence of localized states, dictates molecular adsorbate behavior.
• Observed trends in charge donation and electronic friction show clear signatures of topological phase transitions.
• Engineering topological boundaries and domain walls offers promising pathways for applications in molecular catalysis and sensing.