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1

High-Pressure Phase Transitions and Thermodynamic Behaviors of Cadmium Sulfide

100%

Tan J., Li Y., Ji G.

Acta Physica Polonica A

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2011

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vol. 120

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issue 3

501-506

EN

The pressure-induced phase transitions of cadmium sulfide semiconductor in both zinc-blende and wurtzite structures are investigated by ab initio plane-wave pseudopotential density functional theory with the local density approximation. On the basis of the fourth-order Birch-Murnaghan equation of state, the phase transition pressures P_{t} are determined by the enthalpy criterion. It is found that the phase transitions occur at pressure of 2.57 GPa (zinc blende-rocksalt structure) and 2.60 GPa (wurtzite-rocksalt structure), respectively. The equilibrium structural parameters, elastic constants, and phase transition pressures are calculated and compared with the experimental data available and other theoretical results. According to linear-response approach, the thermodynamic properties such as the free energy, enthalpy, entropy, and heat capacity are also obtained successfully from the phonon density of state.

2

Elastic and Thermodynamic Properties of Anti-Perovskite Type Superconductor MCNi_3 (M = Zn, Cd)

88%

Duan M., Tan J., Ji G., Chen X., Zhu J.

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issue 4

652-658

EN

The elastic and thermodynamic properties of the anti-perovskite superconductor ZnCNi_3 and CdCNi_3 are investigated by first-principles calculations. With the local density approximation as well as the generalized gradient approximation for exchange and correlation, the ground state properties and equation of state are obtained, which agree well with other theoretical calculations and experiments. Furthermore, by the elastic stability criteria, we predict that ZnCNi_3 and CdCNi_3 are not stable above 98.1 GPa and 196.5 GPa, respectively. The dependences of the heat capacity, thermal expansion coefficient, the Grüneisen parameter and bulk modulus (B_{T} and B_{S}) on pressure and temperature for ZnCNi_3 and CdCNi_3 are also obtained successfully.

3

Thermodynamic and Electronic Properties of OsB_2 from First-Principles Calculations

88%

Cheng Y., Yang J., Wang Y., Ji G., Chen X.

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vol. 125

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issue 5

1186-1190

EN

The pressure induced phase transitions of OsB_2 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 OsB_2 has no phase transition temperature from the Orth structure to the Hex structure. Moreover, the dependences of the relative volume V/V_0 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.

4

Theoretical Predictions of Lattice Parameters and Mechanical Properties of Pentaerythritol Tetranitrate under the Temperature and Pressure by Molecular Dynamics Simulations

76%

Tan J. J., Hu C., Li Y., Ge N., Chen T., Ji G.

Acta Physica Polonica A

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2017

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vol. 131

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issue 2

318-323

EN

Molecular dynamics simulations with condensed-phase optimized molecular potentials for atomistic simulation studies force field are performed to investigate the structure, equation of state, and mechanical properties of high energetic material pentaerythritol tetranitrate. The equilibrium structural parameters, pressure-volume relationship and elastic constants at ambient conditions agree excellently with experiments. In addition, fitting the pressure-volume data to the Birch-Murnaghan or Murnaghan equation of state, the bulk modulus B₀ and its first pressure derivative B'₀ are obtained. Moreover, the elastic constants are calculated in the pressure range of 0-10 GPa at room temperature and in the temperature range of 200-400 K at the standard pressure, respectively. By the Voigt-Reuss-Hill approximation, the mechanical properties such as bulk modulus B, shear modulus G, and the Young modulus E are also obtained successfully. The predicted physical properties under temperature and pressure can provide powerful guidelines for the engineering application and further experimental investigations.

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High-Pressure Phase Transitions and Thermodynamic Behaviors of Cadmium Sulfide

Elastic and Thermodynamic Properties of Anti-Perovskite Type Superconductor MCNi_3 (M = Zn, Cd)

Thermodynamic and Electronic Properties of OsB_2 from First-Principles Calculations

Theoretical Predictions of Lattice Parameters and Mechanical Properties of Pentaerythritol Tetranitrate under the Temperature and Pressure by Molecular Dynamics Simulations