Evolutionary Search and Theoretical Study of Silicene Grain Boundaries' Mechanical Properties*

One of the biggest obstacles in building devices using 2D materials is that defects such as grain boundaries (GBs) are almost inevitable during the synthesis process, such defects also provide a fabrication method for tuning properties for different applications. Therefore, to fully realize the potential of 2D materials, such as silicene, studying energetically stable GBs and understanding their impact on material properties is crucial. In this work, using an evolutionary algorithm search with an in-house Tersoff potential surrogate, we predicted multiple phases for the GBs on silicene, including those that were previously unreported to our best knowledge. The correlation between the topological structures, the formation energy, and mechanical properties was studied for these structures, and the research results shed light on various possible atomic structures for silicene GBs and give useful information on their impact on mechanical properties. More importantly, in this work, we demonstrate a generalizable workflow for investigating 2D GB or interfaces based on an evolutionary algorithm.