title: Global structure search and physical properties of Os2C.
abstract: The crystal structures of Os2C were extensively investigated using the structure search method from the first-principles calculations. In contrast to the P6 3 /mmc phase previously proposed as the ground state at ambient pressure, an energetically favorable structure with space group P-6m2 was found more stable at ambient condition. The structural stabilities of the new phase are confirmed by the phonon dispersion and elastic constants. Further calculations indicate that the newly predicted P-6m2 phase is ultra-incompressible with a high bulk modulus of 387 GPa and has a larger ideal shear strength than the P6 3 /mmc phase.
authors.affiliation: Department of Physics, International Centre for Quantum and Molecular Structures, SHU-Solar E R & D Lab, Shanghai University, Shanghai 200444, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Hong
authors.forename: Jian
authors.initials: J
authors.lastname: Lu
authors.forename: Heng
authors.initials: H
authors.lastname: Gao
authors.forename: Wei
authors.initials: W
authors.lastname: Ren
authors.forename: Run
authors.initials: R
authors.lastname: Xu
authors.forename: Fei
authors.initials: F
authors.lastname: Xu
authors.forename: Zhongquan
authors.initials: Z
authors.lastname: Ma
authors.forename: Yanfa
authors.initials: Y
authors.lastname: Yan