Academy of Mathematics and Systems Science, CAS Colloquia & Seminars | Speaker: | 张磊 副教授/研究员,北京大学 | Inviter: | 张硕 副研究员 | Title: | Nucleation of Quasicrystals | Time & Venue: | 2021.12.07 10:00-11:00 科技综合楼311教室 | Abstract: | Despite the fact that tremendous efforts have been made on the study of quasicrystals since their discovery in 1984, nucleation of quasicrystals, viz. the emergence of a quasicrystal from a crystalline phase, still presents an unsolved and challenging problem. The difficulties lie in that quasicrystals and crystals are incommensurate structures in general, so there are no obvious epitaxial relations between them. In this talk, we proposed a saddle dynamics method to solve this problem by applying the Landau theory of phase transitions. We obtained the accurate critical nuclei and transition pathways connecting crystalline and quasicrystalline phases. The results reveal that phase transitions between the crystalline and quasicrystalline phases could follow two possible pathways, corresponding to a one-stage phase transition and a two-stage phase transition involving a metastable lamellar quasicrystalline state, respectively. The proposed computational methodology not only reveals the mechanism of nucleation of quasicrystals, but also paves the way to investigate a wide range of physical problems undergoing the first-order phase transitions. | | | |