Thermodynamic and Electronic Properties of OsB2 from First-Principles Calculations

Y. Chenga, b, J.-W. Yanga, Y.-X. Wanga, G.-F. Jic and X.-R. Chena aCollege of Physical Science and Technology, Sichuan University, Chengdu 610064, China bSchool of Electrical, Computer and Energy Engineering, Arizona State University, AZ 85287-5706, USA cLaboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China

Received: April 9, 2013; In final form: January 26, 2014

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The pressure induced phase transitions of OsB2 from the orthorhombic structure (Orth) to the hexagonal structure (Hex) is investigated by using ab initio plane-wave pseudopotential density functional theory, together with quasi-harmonic Debye model. We find that the pressure-induced phase transition occurs at 2.8 GPa and 12.5 GPa by local density approximation and general gradient approximation, respectively. It is predicted that OsB2 has no phase transition temperature from the Orth structure to the Hex structure. Moreover, the dependences of the relative volume V/V0 on the pressure, thermal expansion coefficient α on the pressure and temperature are also successfully obtained. The electronic properties including energy band, total and partial density of states and electron density difference for two structures are also analyzed. The Mulliken charges and Bond populations for both Orth and Hex structures are also obtained.

DOI: 10.12693/APhysPolA.125.1186 PACS numbers: 71.15.Mb, 61.50.Ks, 67.25.de, 71.20.-b