title: Two-dimensional boron monolayer sheets.
abstract: Boron, a nearest-neighbor of carbon, is possibly the second element that can possess free-standing flat monolayer structures, evidenced by recent successful synthesis of single-walled and multiwalled boron nanotubes (MWBNTs). From an extensive structural search using the first-principles particle-swarm optimization (PSO) global algorithm, two boron monolayers (α(1)- and β(1)-sheet) are predicted to be the most stable α- and β-types of boron sheets, respectively. Both boron sheets possess greater cohesive energies than the state-of-the-art two-dimensional boron structures (by more than 60 meV/atom based on density functional theory calculation using PBE0 hybrid functional), that is, the α-sheet previously predicted by Tang and Ismail-Beigi and the g(1/8)- and g(2/15)-sheets (both belonging to the β-type) recently reported by Yakobson and co-workers. Moreover, the PBE0 calculation predicts that the α-sheet is a semiconductor, while the α(1)-, β(1)-, g(1/8)-, and g(2/15)-sheets are all metals. When two α(1) monolayers are stacked on top each other, the bilayer α(1)-sheet remains flat with an optimal interlayer distance of ~3.62 Å, which is close to the measured interlayer distance (~3.2 Å) in MWBNTs.
authors: CAS Key Lab of Materials for Energy Conversion, Department of Materials Science and Engineering and Hefei National Lab for Physical Materials at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China. xjwu@ustc.edu.cn
authors: Xiaojun
authors: X
authors: Wu
authors: Jun
authors: J
authors: Dai
authors: Yu
authors: Y
authors: Zhao
authors: Zhiwen
authors: Z
authors: Zhuo
authors: Jinlong
authors: J
authors: Yang
authors: Xiao Cheng
authors: XC
authors: Zeng
mesh_terms: D001895:Boron / Q000737:chemistry*; D003198:Computer Simulation; D046911:Macromolecular Substances / Q000737:chemistry; D008567:Membranes, Artificial; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D008567:Membranes, Artificial; D001895:Boron