ReaxFF Simulations of Self-Assembled Monolayers On Silver Surfaces and Nanocrystals

The self-assembled monolayers of alkane thiolates on Ag (111) surfaces andnanoparticles are studied using molecular dynamics. Reactive force fields allowsimulations of very large systems such as nanoparticles of 10 nm. Stable(sqrt(7) X sqrt(7))R19.1{\deg} assemblies are obtained as experimentallyobserved for these systems. Only nanoparticles smaller than 4 nm show aspontaneous restructuration of the metallic core. The preferred adsorption siteis found to be in an on-top position, in good agreement with recent X-rayabsorption near edge structure experiments. Moreover, similar distances betweenthe sulfur headgroups are found on the facets and edges.