Effects of electric field on Rayleigh limit of nanoscale water droplets: molecular dynamics simulation

Abstract

Nanoscale charged water droplets play a significant role in many physical processes, including cloud electrification and electrospray ionization, which have become one research focus. Generally, the maximum value of charge that a droplet can carry is called Rayleigh limit. Here, we investigate the effect of electric field (<0.5 V nm−1) on Rayleigh limit of nanoscale water droplets (r < 5 nm) by molecular dynamics simulation and theoretically qualitative analysis. In the simulation, Rayleigh limit of nanoscale water droplets under various electric fields is investigated based on optimal point charge water model by GROMACS package code. Our study demonstrates that electric field could affect Rayleigh limit by generating the induced charge, changing the surface tension and the droplet shape. Further, we propose the modified Rayleigh limit formula under electric field, with considering the potential energy of deformed charged droplet under strong electric field. The modified formula can qualitatively explain the abnormal trend that Rayleigh limit of nanoscale water droplet (r > 3 nm) decreases first and then increases with the electric field (<0.5 V nm−1) in the simulation.