Papers by Author: Ping Qian

Abstract: The phase stability and site preference of transition metal carbides Cr in Fe7-xCrxC3 are studied based on the pair potentials obtained by the lattice inversion method. The lattice constants and cohesive energy of Fe7-xCrxC3 with the content x are calculated. The results show that Cr atoms substitute for Fe with a strong preference for the 6c1 sites and the order of site preference is 6c1, 6c2 and 2b. Calculated lattice parameters are in good agreement with the experimental data. Moreover, the total and partial phonon densities of states are first evaluated for the Fe7-xCrxC3 compounds with the hexagonal structure. We also provide some information on the vibrational properties of transition metal carbides, such as the specific heat and Debye temperature were also evaluated.

Abstract: We systematically performed first-principles investigations of the structural properties, electron energy band, and densities of states (DOS) for ThO2. All calculations were carried out using the local density approximation (LDA), generalized gradient approximation (GGA), LDA+U, and GGA+U approaches. We also compared our findings with experimental data and other calculations. The lattice parameter obtained using the GGA+U agrees well with the experimental value.

Abstract: An atomistic study is presented on the phase stability, interatomic distances and lattice parameters of the new actinide intermetallic compounds AFe₂Al₁₀ (A = Th, U). Calculations are based on a series of interatomic pair potentials related to the actinides and transition metals, which are obtained by lattice inversion method. The cohesive energy of AFe₂Al₁₀ with two possible structures of YbFe₂Al₁₀-type and ThMn₁₂-type are calculated and compared with each other. Calculated lattice parameters of AFe₂Al₁₀ are found to agree with reports in the literatures. In particular, the phonon densities of states, vibrational entropy and Debye temperature related to dynamic phenomena are evaluated for the first time.

Abstract: The site preference and thermodynamic properties of UT_xAl_12-x (T = Zr, Nb, Mo and Fe) and their related hydrides are studied based on the pair potentials obtained by the lattice inversion method. The calculated result demonstrates that the stabilizing elements Zr, Nb, or Mo prefer to substitute for Al in 8i sites; and Fe atom preferentially substitutes for Al in the 8f site. The interstitial H atoms only occupy 2b interstitial sites in UT_xAl_12-x. The calculated lattice parameters coincide with the experimental values. In addition, the total and partial phonon densities of states are first evaluated for these compounds.

Abstract: An atomistic simulation of the structural properties of the new ternary A₄Rh₁₃Si₉ and A₄Ir₁₃Si₉ compounds, where A is Th, U, has been carried out using interatomic pair potentials based on the lattice inversion method. The calculated lattice parameters are corresponding to the experimental results. The phase stability of the intermetallics A₄Rh₁₃Si₉ and A₄Ir₁₃Si₉ is tested by high temperature disturbance under the control of the pair potentials. Moreover, the phonon densities of states, specific heat and vibrational entropy related to dynamic phenomena are evaluated for the first time. The method utilized in the present investigation offers a rather easy and direct way to study the structural and vibrational properties of A₄Rh₁₃Si₉ and A₄Ir₁₃Si₉.

Abstract: An atomistic simulation is presented on the phase stability and lattice parameters of the new actinide intermetallic compounds A₃Ni₅Al₁₉ (A = Th, U). Calculations are based on a series of interatomic pair potentials related to the actinides and transition metals, which are obtained by lattice inversion method. Calculated lattice constants are found to agree with a report in the literature. It is noted that, the total and partial phonon densities of states are first evaluated for the A₃Ni₅Al₁₉ (A = Th, U) compounds. The analysis for the inverted potentials explains qualitatively the contributions of different atoms to the vibrational modes.