zhu chunye - Academia.edu (original) (raw)

Papers by zhu chunye

Physica B-condensed Matter, 2011

First-principles calculations have been performed on NaAlH4 using the generalized gradient approx... more First-principles calculations have been performed on NaAlH4 using the generalized gradient approximation pseudopotential method. The predicted β-NaAlH4 (α-LiAlH4-type) structure is energetically more favorable than α-NaAlH4 for pressures over 15.9GPa, which is apparently correlated with the experimental transition pressure 14GPa. This transition is identified as first-order in nature with volume contractions of 1.8%. There is no pressure-induced softening behavior from our

Chinese Physics Letters, Dec 1, 2010

Using density-functional-theory calculations, a monoclinic metallic post-ζ phase (space group C2/... more Using density-functional-theory calculations, a monoclinic metallic post-ζ phase (space group C2/c) is predicted at 215 GPa. The calculated phonon dispersion curves suggest that this structure is stable at least up to 310 GPa. Oxygen remains a molecular crystal and there is no dissociation in the related pressure range. Moreover, it is found that the phase transition from ζ to post-ζ

physica status solidi (b), 2011

We present a study on NaBH4 under high pressure by using the ab initio pseudopotential plane‐wave... more We present a study on NaBH4 under high pressure by using the ab initio pseudopotential plane‐wave method. The calculations show that a structural phase transition takes place at 10.91 GPa from the β‐NaBH4 structure (tetragonal‐$P{\bar {4}}{\rm 2}_{{\rm 1}} c$) to the γ‐NaBH4 structure (orthorhombic‐Pnma). Band‐structure calculation reveals that the two phases show an insulator behaviour with a finite energy gap. There is no pressure‐induced softening behaviour from our calculated phonon dispersion curves near the phase transition pressure. We also characterize charge transfer and Mulliken population analyses of these structures. The Mulliken population analyses indicate that the β‐NaBH4 phase is expected to be the most promising candidate for hydrogen storage.

Physica B: Condensed Matter, 2011

Dalton Transactions, 2012

A theoretical investigation on structural and thermodynamic properties of 11-type iron-based supe... more A theoretical investigation on structural and thermodynamic properties of 11-type iron-based superconductor FeSe at high pressure and high temperature was performed by employing the first-principles method based on the density functional theory. Some structural parameters of FeSe in both tetragonal and hexagonal phases are reported. According to the fourth-order Birch-Murnaghan equation of states, the transition pressure P(t) of FeSe from the PbO-type phase to the NiAs-type phase was determined. The calculated results are found to be in good agreement with the available experimental data. Based on the quasi-harmonic Debye model, the pressure and temperature dependence of the thermodynamic properties for hexagonal phase FeSe were investigated. Our theoretical calculations suggest that the pressure and temperature have significant effects on the heat capacity, vibrational internal energy, vibrational entropy, vibrational Helmholtz free energy, thermal expansion coefficient and Debye temperature. Even though few theoretical reports on the structural properties of FeSe are found in the current literature, to our knowledge, this is a novel theoretical investigation on the structural and thermodynamic properties of FeSe at high temperature. We hope that the theoretical results reported here can give more insight into the structural and thermodynamic properties of other iron-based superconductors at high temperature.

Chinese Physics Letters, 2010