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We have performed first principles calculations for the electronic, dynamical, and thermodynamic properties of α-U using the projector augmented wave (PAW) method. The optimized lattice parameters, equilibrium volume, atomic energy, bulk modulus, and its pressure derivative are close to the experimental data and other calculations. To evaluate the strong on-site Coulomb repulsion among the localized uranium 5f electrons, the generalized gradient approximation (GGA)+ U formalism have been adopted. It is shown that the total DOS at the Fermi energy level mainly comes from the contribution of narrow f band, the electron correlation effect is small for metallic bands of uranium. In particular, the phonon spectrum of α-U is calculated within density functional perturbation theory (DFPT) as well as the small displacement method, the coincidence between our calculations and Crummett et al.'s inelastic neutron scattering measurements indicates that both phonon methods based on PAW scheme are reasonable to capture the anomalous phonon properties of α-U. The calculated dynamical properties of uranium under pressure suggest that Cmcm uranium should be stabilized dynamically at least up to 100 GPa, which accords with X-ray diffraction experimental results of Le Bihan et al. The thermodynamic functions of α-U under high temperature and high pressure are also obtained further. [ABSTRACT FROM AUTHOR]

We perform detailed first principles calculations of the structural parameters at zero pressure and high pressure, the elastic properties, phonon dispersion relation, and ideal strengths of U2Mo with the C11b structure. In contrast to previous theoretical studies, we show that the I4/mmm structure is indeed a mechanically and dynamically unstable phase, which is confirmed by the negative elastic constant C66 as well as the imaginary phonon modes observed along the Σ1–N–P line. The calculations of ideal strengths for U2Mo are performed along the [100], [001], and [110] directions for tension and on (001)[010] and (010)[100] slip systems for shear load. The ideal shear strength is about 8.1 GPa, much smaller than a tension of 18–28 GPa, which indicates that the ductile U2Mo alloy will fail by shear rather than by tension. [ABSTRACT FROM AUTHOR]

Recent work has relatively comprehensively studied the quantum discord, which is supposed to account for all the nonclassical correlations present in a bipartite state (including entanglement), and provide computational speedup and quantum enhancement even in separable states. Firstly, we introduce several different indicators of nonclassical correlations, including their definitions and interpretations, mathematical properties, and the relationship between them. Secondly, we review two major topics of quantum discord. One is the remarkable behavior at quantum phase transitions. The pairwise quantum discord for nearest neighbors as well as distant spin pairs can perfectly signal the critical behavior of many physical models, even at finite temperatures. The other is quantum discord dynamics in open systems, especially for "system-spin environment" models. Quantum discord is more robust than entanglement against external perturbations. It can be created, greatly amplified or protected under certain conditions, and presents promising applications in quantum technologies such as quantum computers. [ABSTRACT FROM AUTHOR]