A challenge in synthesizing metal nanocrystals is understanding the growth of nanocrystal seeds. Seeds play a critical role in nanostructure formation, as the shape of the seed often determines the final nanocrystal shape.  In this work, we determine the minimum free-energy distribution of shapes of Ag, Cu, Pd, and Au nanocrystals with 100-300 atoms at temperatures ranging from room temperature to melting.  Our studies reveal a diverse array of shapes that vary with nanocrystal size and temperature.  Interestingly, there are size ranges for each metal over which the shape distributions change drastically with size - in some cases with the addition of a single atom.  These sizes are distinct from the magic sizes and their discovery offers the possibility of selecting processing routes for achieving particular nanocrystal sizes in syntheses.  Time permitting, I will also discuss our kinetic studies of the shape transformations of these nanocrystals.

Nanocrystals at the crossroads:  Parallel tempering molecular dynamics of nanocrystal shape transitions

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ACS Spring 2023

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