ABSTRACT:
Simple, inorganic atoms can arrange themselves in myriad ways, both ordinary and extraordinary, that have become the foundation of nanotechnology. Unlocking the mysteries of metal nanocrystal growth and assembly has been a pursuit in our research for the past decade. In this talk, I will discuss our efforts to develop the theoretical capability to capture the intricacies of nanocrystal growth and our application of these methods to describe experimental mysteries.

I will discuss the profound and synergistic role of halides and organic capping agents in promoting facet-selective nanocrystal growth and selective assembly. We use first-principles density-functional theory calculations, along with auxiliary methods, to demonstrate how halides affect surface diffusion and facet-specific nanocrystal interactions in multiple systems, ranging from the growth of Cu nanowires and plates to the assembly of Au nanocrystals to the formation of hierarchical Pt nanocrystals via facet-selective aggregation. Early in the growth process, nanocrystals in the 1-2 nm size range are fluxional and we have used enhanced sampling methods, originally developed to study biomolecules, together with machine learning to uncover their structures and shape transformations and to learn useful information for catalysis.