Ice crystal structure melting: insights from molecular dynamics simulations

Climate change poses many new engineering challenges, such as the increasing number of ice falling incidents on cables of cable-supported bridges. This presents a significant risk to bridge users and society. A thorough understanding of the ice melting process and the impact of weather conditions on its progression is pivotal to elucidate the mechanisms of ice detachment from bridge stay cables and predict its occurrence to prevent any potential ice falling events. The current paper presents a numerical investigation of the transition process from ice to water based on molecular dynamics (MD) simulations using three water models of SPC/E, TIP3P and TIP4P. The water phase change in a piece of pure ice crystal consisting of 3072 atoms is tracked via the tetrahedral order parameter. The performance of these three water models is evaluated based on the predicted ice melting process, melting temperature, numerical stability and computational cost. The impact of thermal conditions, cut-off distance, and ice crystal structure size on the simulated ice melting process are assessed. Ice melting characteristics are revealed by examining the ice cube's internal structure at the molecular level. In addition, the computational efficiency of various CPUs and GPUs in performing MD simulations are compared. The findings from this study not only enhance the understanding of ice melting process at the molecular level, but also provide valuable guidance for optimizing practices in simulations prior to conducting more complex simulations of ice detachment from stay cables.