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The elastic, thermodynamic, and electronic properties of fluorite RuO_2 under high pressure are investigated by plane-wave pseudopotential density functional theory. The optimized lattice parameters, elastic constants, bulk modulus, and shear modulus are consistent with other theoretical values. The phase transition from modified fluorite-type to fluorite is 88 GPa (by localized density approximation, LDA) or 115.5 GPa (by generalized gradient approximation, GGA). The Youngs modulus and Lames coefficients are also studied under high pressure. The structure turned out to be stable for the pressure up to 120 GPa by calculating elastic constants. In addition, the thermodynamic properties, including the Debye temperature, heat capacity, thermal expansion coefficient, Gruneisen parameter, and Poissons ratio, are investigated. A small band gap is found in the electronic structure of fluorite RuO_2 and the bandwidth increases with the pressure. Also, the present mechanical and electronic properties demonstrate that the bonding nature is a combination of covalent, ionic, and metallic contributions.
Using first-principles calculations within the generalized gradient approximation, we predicted the lattice parameters, elastic constants, vibrational properties, and electronic structure of cementite (Fe3C). Its nine single-crystal elastic constants
First-principles calculations through a FLAPW-GGA method for six possible polymorphs of ruthenium mononitride RuN with various atomic coordination numbers CNs: cubic zinc blende (ZB) and cooperite PtS-like structures with CNs = 4; cubic rock-salt (RS
Zirconium alloys are used as nuclear fuel cladding material due to their mechanical and corrosion resistant properties together with their favorable cross-section for neutron scattering. At running conditions, however, there will be an increase of hy
The high pressure structural properties of bismuth oxide Bi2SiO5 have been investigated up to 28 GPa using in situ powder synchrotron X-ray diffraction and up to 50 GPa with DFT calculations. The monoclinic structure is found to persist up to about 2
The full-potential linearized augmented plane wave method with the generalized gradient approximation for the exchange-correlation potential (FLAPW-GGA) is used to predict the electronic and elastic properties of the newly discovered superconducting