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Phase transitions are fundamental phenomena in statistical physics and thermodynamics. Almost four decades ago, a first-order-like non-equilibrium glass-glass transition (GGT) was discovered in water with two forms of amorphous ices were identified. Subsequently, GGT was observed in other materials, including water-like complex substances[1,2], colloids, particulate matter, polymers, liquid crystals, etc. However, statistical physics, thermodynamics, and condensed matter physics cannot describe the non-equilibrium phase transition of complex disordered systems. As a century problem in the 125th anniversary of Science, describing non-equilibrium phase transitions, such as glass transition and glass-glass transition, has been challenging due to the lack of well-established theories.

Although many challenges are faced, specific phenomena could still be focused on as interesting directions, one of them is the confined liquids in supercooled region. Liquids in confined geometries has obvious relevance in biology, geology, and other areas where the material properties are strongly dependent on the amount and behavior of liquids themselves in these types of materials, especially water[3]. Additionally, the crystallization of liquids confined at the nanoscale plays an important role in scientific and engineering applications, yet crystallization at the nanoscale is not well understood. Using molecular dynamics simulations, we study the crystallization of a confined liquid characterized by isotropic pair interactions with water-like properties, and find that increasing the liquid–surface interaction strength favors crystallization for the case of structureless surfaces, while it tends to suppress crystallization for the case of amorphous surfaces[4].

The behavior of amorphous solids is also attractive in this region. Glasses and other amorphous solids represent a class of materials that is both relatively commonplace and highly complex. Despite their familiarity, the fundamental physics underlying several common features of glasses is not yet well understood. While amorphous materials respond elastically to small applied strain, they undergo irreversible structural rearrangement for moderate deformation that is difficult to characterize and predict. Recently, significant effort has been put into forming structure-dynamics predictions for the failure behavior of disordered solids. These works attempt to identify structural precursors to plastic deformation, which occurs when glasses become unstable. We investigate the topological characteristics of the eigenvector field of the vibrational excitations of two-dimensional model glasses, and provide a link between the structure of glasses prior their deformation and the plastic events during deformation[5].

References：

1. G. Sun, L. Xu, N. Giovambattista. "Anomalous Features in the Potential Energy Landscape of a Waterlike Monatomic Model with Liquid and Glass Polymorphism", Phys. Rev. Lett. 120, 035701 (2018)

2. Y. Liu, G. Sun, L. Xu. "Glass polyamorphism in gallium: Two amorphous solid states and their transformation on the potential energy landscape", The Journal of Chemical Physics, 154, 134503 (2021)

3. S. Cerveny, F. Mallamace, J. Swenson, M. Vogel, and L. Xu. 'Confined Water as Model of Supercooled Water'. Chemical Reviews (2015)

4. G. Sun, N. Giovambattista, E. G. Wang, and L. Xu*, et al.“Effects of surface structure and solvophilicity on the crystallization of confined liquids”, Soft Matter 9, 11374 (2013)

5. Z. Wu, Y. Chen, W. Wang, W. Kob, L. Xu, "Topology of vibrational modes predict plastic events in glasses", Nat. Commun. (2023)