title: Crystal Structures, Stabilities, Electronic Properties, and Hardness of MoB2: First-Principles Calculations.
abstract: On the basis of the first-principles techniques, we perform the structure prediction for MoB2. Accordingly, a new ground-state crystal structure WB2 (P63/mmc, 2 fu/cell) is uncovered. The experimental synthesized rhombohedral R3̅m and hexagonal AlB2, as well as theoretical predicted RuB2 structures, are no longer the most favorite structures. By analyzing the elastic constants, formation enthalpies, and phonon dispersion, we find that the WB2 phase is thermodynamically and mechanically stable. The high bulk modulus B, shear modulus G, low Poisson's ratio ν, and small B/G ratio are benefit to its low compressibility. When the pressure is 10 GPa, a phase transition is observed between the WB2-MoB2 and the rhombohedral R3̅m MoB2 phases. By analyzing the density of states and electron density, we find that the strong covalent is formed in MoB2 compounds, which contributes a great deal to its low compressibility. Furthermore, the low compressibility is also correlated with the local buckled structure.
authors.affiliation: Department of Optoelectronic Science & Technology, College of Electrical & Information Engineering, Shaanxi University of Science & Technology , Xi'an 710021, China.
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Ding
authors.affiliation: Department of Optoelectronic Science & Technology, College of Electrical & Information Engineering, Shaanxi University of Science & Technology , Xi'an 710021, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Shao
authors.affiliation: Department of Optoelectronic Science & Technology, College of Electrical & Information Engineering, Shaanxi University of Science & Technology , Xi'an 710021, China.
authors.forename: Fang-Hui
authors.initials: FH
authors.lastname: Zhang
authors.affiliation: Department of Physics, Nanyang Normal University , Nanyang 473061, China.|Beijing Computational Science Research Center , Beijing 100084, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Lu
authors.affiliation: Department of Optoelectronic Science & Technology, College of Electrical & Information Engineering, Shaanxi University of Science & Technology , Xi'an 710021, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Ding
authors.affiliation: Department of Optoelectronic Science & Technology, College of Electrical & Information Engineering, Shaanxi University of Science & Technology , Xi'an 710021, China.
authors.forename: Shu Ya
authors.initials: SY
authors.lastname: Ning
authors.affiliation: Physics Department, Sichuan Normal University , Chengdu 610068, China.
authors.forename: Xiao Fen
authors.initials: XF
authors.lastname: Huang