Structural transition of a nanodroplet under an alternating electric field: Understandings and predictions from a dynamic density functional theory

Abstract

Alternating current (AC) electric field is an efficient means in controlling the nanostructure of a material but the mechanism is not so clear in many systems. We introduced a dynamic density functional theory (DDFT) to mimic the formation and evolution of a nanodroplet/nanocluster under an AC electric field. The prediction from DDFT is qualitatively consistent with real-world experiments and molecular simulations. The influence from the AC electric field is summarized into a diagram and the transition line can be fitted into an empirical function. It seems the crystallization mechanism is different at high and low temperatures, in which the AC electric field is a favorable and unfavorable condition for crystallization, respectively. The crystallization can be divided into two steps which corresponds to the change of order parameter and free energy, respectively. Additionally, different AC waves results in similar nanostructures and the pulse wave has the highest order parameter.