Unraveling medium-range order and melting mechanism of ZIF-4 under high temperature

Glass formation in zeolitic imidazolate frameworks (ZIFs) has garnered significant attention in the field of metal-organic frameworks (MOFs) in recent years. Numerous works have been conducted to investigate the microscopic mechanisms involved in the melting-quenching process of ZIFs. Understanding the density variations that occur during the melting process of ZIFs is crucial for comprehending the origins of glass formation. However, conducting large-scale simulations has been challenging due to limitations in computational resources. In this work, we used deep-learning methods to accurately construct a potential function that describes the atomic-scale melting behavior of ZIF-4. The results revealed the spatial heterogeneity associated with the formation of low-density phases during the melting process of ZIF-4. This work discusses the advantages and limitations of applying deep-learning simulation methods to complex structures like ZIFs, providing valuable insights for the development of machine-learning approaches in designing MOF glasses. Mid-range structural evolution of the ZIF-4 high-temperature melting process. image