Phonon spectrum, thermodynamic properties, and pressure-temperature phase diagram of uranium dioxide
TLDR
In this paper, the structural phase transition and the mechanical and thermodynamic properties of UO${}_{2}$ by means of the local density approximation (LDA)+$U$ approach were analyzed.Abstract:
We present a study of the structural phase transition and the mechanical and thermodynamic properties of UO${}_{2}$ by means of the local density approximation (LDA)+$U$ approach. A phase transition pressure of 40 GPa is obtained from theory at 0 K, and agrees well with the experimental value of 42 GPa. The pressure-induced enhancements of elastic constants, elastic moduli, elastic wave velocities, and Debye temperature of the ground-state fluorite phase are predicted. The phonon spectra of both the ground state fluorite structure and high-pressure cotunnite structure calculated by the supercell approach show that the cotunnite structure is dynamically unstable under ambient pressure. Based on the imaginary mode along the $\ensuremath{\Gamma}$$\ensuremath{-}$$X$ direction and soft phonon mode along the $\ensuremath{\Gamma}$$\ensuremath{-}$$Z$ direction, a transition path from cotunnite to fluorite has been identified. We calculate the lattice vibrational energy in the quasiharmonic approximation using both first-principles phonon density of state and the Debye model. The calculated temperature dependence of lattice parameter, entropy, and specific heat agrees well with experimental observations in the low temperature domain. The difference of the Gibbs free energy between the two phases of UO${}_{2}$ has predicted a boundary in the pressure-temperature phase diagram. The solid-liquid boundary is approximated by an empirical equation using our calculated elastic constants.read more
Citations
More filters
Journal ArticleDOI
Advances of 2D bismuth in energy sciences.
Xuhai Liu,Xuhai Liu,Shengli Zhang,Shiying Guo,Bo Cai,Shengyuan A. Yang,Fukai Shan,Martin Pumera,Haibo Zeng +8 more
TL;DR: It is hoped that the improved manipulation techniques of bismuthene, along with its unique properties, might even enable 2D Bi to play an important role in future energy-related twistronics.
Journal ArticleDOI
Multifaceted Modularity: A Key for Stepwise Building of Hierarchical Complexity in Actinide Metal–Organic Frameworks
Ekaterina A. Dolgopolova,Otega A. Ejegbavwo,Corey R. Martin,Mark D. Smith,Wahyu Setyawan,Stavros Karakalos,Charles H. Henager,Hans-Conrad zur Loye,Natalia B. Shustova +8 more
TL;DR: The combination of a multistep synthetic approach with homogeneous actinide distribution and moderate solvothermal conditions could make MOFs an exceptionally powerful tool to address fundamental questions responsible for chemical behavior of An-based extended structures and, therefore, shed light on possible optimization of nuclear waste administration.
Journal ArticleDOI
NCrystal: A library for thermal neutron transport
TL;DR: NCrystal as mentioned in this paper is an open source software package for modeling thermal neutron transport, which facilitates Monte Carlo-based transport simulations and focuses on interactions in both mosaic single crystals as well as polycrystalline materials and powders.
Journal ArticleDOI
Spectroscopic Raman characterization of rutherfordine: a combined DFT and experimental study
TL;DR: A rutherfordine mineral was studied by means of Raman spectroscopy combined with first principle calculations based on the density functional theory (DFT) method and the pseudopotential of a uranium atom was generated and its performance was evaluated for a series of uranium-containing minerals.
References
More filters
Book
Introduction to solid state physics
TL;DR: In this paper, the Hartree-Fock Approximation of many-body techniques and the Electron Gas Polarons and Electron-phonon Interaction are discussed.
Journal ArticleDOI
Introduction to Solid State Physics
TL;DR: Kind's new edition is to be welcomed as mentioned in this paper, with a revised format and attractive illustrations, and with the inclusion of much new material this book has become one of the best sources for undergraduate teaching, likely to give the student a wish to dig deeper into the solid state.
Related Papers (5)
Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set.
Georg Kresse,Jürgen Furthmüller +1 more