Simulating Thermally-Driven Crystallization of Gold Nanoparticles Under a Temperature Cycle

Ordered crystal growth in nanoparticle systems is essential to the development of nanomaterials, for applications ranging from semiconductors for nanoelectronics to lenses for optical imaging. Conventional methods for growing nanoparticle crystals often require heating and cooling over extended periods and are thus time- and resource-consuming. Toggled illumination, which involves heating nanoparticles by turning a light source on and off periodically, offers a promising way to grow a high-quality crystal more quickly and with less energy input than conventional methods. To model crystallization under conditions similar to toggled illumination, we used molecular dynamics simulations to subject a system of nanoparticles to a two-temperature cycle. We first identified a temperature range between the melting and nucleation regimes of the system. Then, we cycled the system with different frequencies and dwell times at each temperature and quantified the order of the resulting crystals and the dynamics of the system, tracking the relationship between cycle parameters, crystal phase and structure. By analyzing the effect of toggled heating on crystal growth, we aim to obtain fundamental insights that will facilitate precise experimental control of nanoparticle growth.