Title: Researcher, doctoral Supervisor
Contact number:
Department: Computational Physics
E-mail: yanweili@bit.edu.cn
Address: 406 Building, Information Center, Beijing University of Technology, Haidian District, Beijing/A317A Building, School of Physics, Beijing Institute of Technology, Fangshan District, Beijing
This research group explores and understands the interesting physical properties of soft matter systems based on computer simulation. The research system can involve complex systems such as crystals, non-crystals, active substances, and cells. The research direction involves 1) crystallization and melting mechanism in different dimensions; 2) Structure and dynamics of amorphous systems; 3) Morphology, phase behavior and dynamics of cytoskeleton; 4) Assembly structure of non-centrosymmetric system.
2007-2011 Bachelor of Science, School of Chemical Engineering, China University of Mining and Technology
2011-2016 Doctor of Science in Polymer Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences
2016-2020 Postdoctoral Fellow, School of Mathematical Physics, Nanyang Technological University, Singapore
2020-present Professor, School of Physics, Beijing Institute of Technology
1. Crystallization and melting mechanisms in different dimensions
In a three-dimensional system, the liquid crystal transition occurs as a first-order phase transition, with nucleation and growth processes dominating the crystallization behavior of the system. Unlike three-dimensional systems, the transition from two-dimensional crystals to liquids is more complex. This is because there may be an intermediate hexagonal phase between crystals and liquids, and the transition from hexagonal phase to liquid can be either a continuous phase transition or a first-order phase transition. Controlling the parameters of the regulatory system to control the two-dimensional crystallization or melting mechanism, as well as understanding the internal control factors of the two-dimensional melting mechanism, are of great significance and challenges. We optimized the spatial correlation function that characterizes the ordered position of two-dimensional systems and used molecular dynamics simulations to study the effect of attractive interactions on the two-dimensional melting mechanism of single component systems. We found that attractive interactions induce discontinuous phase transitions and suppress hexagonal phases, which expands the van der Waals fluid phase diagram; In a multi-component system, the competitive effects of different melting paths on the melting mechanism were revealed, and defect density judgment criteria for different phase stability were expanded and established< br>
2. Structure and dynamics of amorphous systems
During the process of liquid cooling, it may not crystallize below the crystallization temperature, forming an undercooled liquid. Further cooling, the undercooled liquid undergoes a glass transition to form an amorphous solid. During the liquid amorphous solid transition process, the viscosity of the system can increase by nearly 14 orders of magnitude, while its static structure remains unchanged and maintains a long-range disordered state, which is completely different from the liquid crystalline transition. In addition, during the amorphous liquid-solid transition process, the dynamics of the system become slower and slower, and the dynamic correlation function shows a two-step relaxation, accompanied by complex and interesting phenomena such as different particle velocities in different regions of the system. The inherent nature and correlation between the structure and dynamics of amorphous systems are recognized challenges in fields such as statistical physics, soft matter physics, and polymer physics< br>
In response to this issue, we have conducted a series of works using molecular dynamics simulation methods, such as elucidating the influence of long wavelength fluctuations on two-dimensional liquids, which explains the reasons for the observation of two-dimensional liquid singular dynamics in experiments and simulations over the past 50 years; It was found that relaxation and diffusion have different responses to undercooling during the process of glass system approaching the glass transition point, which may be the inherent essence of causing the glass system to deviate from the Stokes Einstein relationship; Drawing inspiration from the idea of point-to-point correlation, the relationship between static correlation length and system undercooling was studied. It was found that in metallic glass systems, the coupling between the two is good, while in systems with Lennard Jones interactions, the coupling in the deep undercooling zone is weak; Clarify the influence of local density on dynamics; The innovative proposal of plastic length can better predict the dynamics of glass systems< br>
3. Phase behavior of cellular systems
Based on the Voronoi model, we studied the ordered disordered transition of cellular systems under two-dimensional thermal equilibrium and non-equilibrium conditions. We found that such systems have an intermediate hexagonal phase under strong deformable conditions, while there is no intermediate hexagonal phase under weak deformable conditions. This result provides insights into the mechanism of transition between epidermal cells (solid-like phase) and stromal cells (liquid-like phase)< br>
4. Non centrosymmetric material design
Asymmetric particle systems exhibit rich phase behavior, and studying their solidification process can provide theoretical guidance for material design. We collaborated with experimental subjects to study the solidification process of a four sided kite shaped system, revealing its melting and glass transition mechanisms< br>
Low temperature configuration diagram of a four sided kite shaped system (left), simulation and experimental comparison of radial distribution functions at different densities (right)