Large-Scale Atomistic Simulations of Environmental Effects on the Formation and Properties of Molecular Junctions

TL;DR

This study uses advanced atomistic simulations to explore how environmental factors and electrode spacing influence the formation and structure of molecular junctions, revealing key dependencies on monolayer density and tip geometry.

Contribution

It introduces an updated simulation approach that accounts for environmental effects and electrode geometry, providing new insights into molecular junction formation.

Findings

Multi-molecule junctions form at low monolayer density.

Single-molecule junctions are favored at high monolayer density.

Tip geometry and monolayer interactions significantly influence bonding geometry.

Abstract

Using an updated simulation tool, we examine molecular junctions comprised of benzene-1,4-dithiolate bonded between gold nanotips, focusing on the importance of environmental factors and inter-electrode distance on the formation and structure of bridged molecules. We investigate the complex relationship between monolayer density and tip separation, finding that the formation of multi-molecule junctions is favored at low monolayer density, while single-molecule junctions are favored at high density. We demonstrate that tip geometry and monolayer interactions, two factors that are often neglected in simulation, affect the bonding geometry and tilt angle of bridged molecules. We further show that the structures of bridged molecules at 298 and 77 K are similar.