UROP Proceedings 2022-23

School of Science Department of Physics 60 Organic Molecular Beam Deposition in Ultra-high Vacuum Supervisor: LIN, Nian / PHYS Student: FENG, Yifei / PHYS Course: UROP1000, Summer Exfoliation is one of the methods for fabricating two-dimensional (2D) materials, and mechanical exfoliation has played an important role since the discovery of the two-dimensional material graphene. As a member of two-dimensional materials, Molybdenum Disulfide (MoS2) has a structure with a molybdenum atom at the center and a sulfur atom at the top and bottom. According to the mechanism of exfoliation, the smaller the fragments, the easier it is to exfoliate, and the stronger interaction between gold and sulfur will affect the results of exfoliation. In the report, an attempt was made to increase the coverage of two-dimensional materials by controlling the fragment size and replacing the substrate with gold. Monte Carlo Simulation of 2D Supramolecular Assembly Supervisor: LIN, Nian / PHYS Student: HUI, Lik Hang Alpha / PHYS Course: UROP4100, Fall UROP4100, Spring UROP4100, Summer In this report, we would be doing simulations with supramolecular assembly incorporating the Kinetic Monte Carlo (KMC) scheme using Fortran and user graphic interface implemented with GTK-Fortran (Magnin et al, 2019). We study the behavior of 2 systems, 2 simple types of atoms, and square molecules. In the former system, we try to quantify the cooperativity effect through the reaction constant with the system in equilibrium. In the latter system, we prepared seeds of different sizes and different structures to investigate how the initial conditions may affect the final saturation result. We would also briefly discuss a new algorithm to build Kagome seed on a hexagonal plane ring by ring. Monte Carlo Simulation of 2D Supramolecular Assembly Supervisor: LIN, Nian / PHYS Student: ZHAO, Heze / SSCI Course: UROP1000, Summer In this UROP1000 report, we present a fundamental investigation into the kinetic Monte Carlo (KMC) method, and study one particular system of KMC simulations. The report begins with introducing the Monte Carlo method and the motivation for KMC. Then we walk through the basic theories and algorithm of KMC, together with the calculation of the rate constants and simplification to lattice KMC. More advanced topics and algorithm variants are briefly mentioned. Finally we explain the mechanism and simulation outcomes of a hands-on lattice KMC system of cross shaped molecules. Running the simulations on the system, we obtain insights on the factors impacting the formation of island-shapes.