  Using molecular dynamics simulations, we study the impact of physisorbing
adsorbates on the structural and mechanical evolution of gold nanowires (AuNWs)
undergoing elongation. We used various adsorbate models in our simulations,
with each model giving rise to a different surface coverage and mobility of the
adsorbed phase. We find that the local structure and mobility of the adsorbed
phase remains relatively uniform across all segments of an elongating AuNW,
except for the thinning region of the wire where the high mobility of Au atoms
disrupts the monolayer structure, giving rise to higher solvent mobility. We
analyzed the AuNW trajectories by measuring the ductile elongation of the wires
and detecting the presence of characteristic structural motifs that appeared
during elongation. Our findings indicate that adsorbates facilitate the
formation of high-energy structural motifs and lead to significantly higher
ductile elongations. In particular, our simulations result in a large number of
monatomic chains and helical structures possessing mechanical stability in
excess of what we observe in vacuum. Conversely, we find that a molecular
species that interacts weakly (i.e., does not adsorb) with AuNWs worsens the
mechanical stability of monatomic chains.
