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The physical properties including structural, electronic, vibrational and thermodynamic properties of Zr1−xHfxCo (x is the concentration of constituent element Hf, and changes from 0 to 1) are investigated in terms of the ABINIT program. The results reveal that all of Zr1−xHfxCo have similar physical properties. When Hf concentration x gradually increases from 0.0 to 1.0, the lattice constant decreases from 3.217 Å to 3.195 Å very slowly. The calculated density of states (DOS) indicates that the metallic nature is enhanced and the electrical conductivity turns better with the increase of Hf. Moreover, as Hf concentration increases from 0 to 1, the Fermi energy gradually increases from −6.96 eV to −6.21 eV, and the electronic density of states at the Fermi level decreases from 2.795 electrons/eV f.u. down to 2.594 electrons/eV f.u., both of which imply the decrease of chemical stability. The calculated vibrational properties show that the increase of Hf concentration from 0 to 1 causes the maximum vibrational frequency to decrease gradually from about 223 cm−1 to 186 cm−1, which suggests a lower dispersion gradient and lower phonon group velocities for these modes. Finally, the phonon related thermodynamic properties are obtained and discussed. [ABSTRACT FROM AUTHOR]

The structures, elasticities, sound velocities, and electronic properties of anhydrous and hydrous fayalite (Fe2SiO4 and Fe1.75H0.5SiO4) under high pressure have been investigated by means of the density functional theory within the generalized gradient approximation (GGA) with the on-site Coulomb energy being taken into account (GGA+U). The optimized results show that H atoms prefer to substitute Fe atoms in the Fe1 site. Compared with the anhydrous fayalite Fe2SiO4, the mass density, elastic moduli, and sound velocities of Fe1.75H0.5SiO4 slightly decrease. According to our data, adding 2.3 wt% water into fayalite leads to reductions of compressional and shear wave velocities ( and ) by 3.4%–7.5% and 0.3%–3.4% at pressures from 0 GPa to 25 GPa, respectively, which are basically in agreement with the 2%–5% reductions of sound velocity obtained by the experimental measurement in the low velocity zones (LVZ). Based on the electronic structure, the valence and conduction bands are slightly broader for hydrous fayalite. However, hydrous fayalite keeps the insulation characteristics under the pressures up to 30 GPa, which indicates that hydration has little effect on its electronic structure. [ABSTRACT FROM AUTHOR]

The electronic, elastic, vibrational, and thermodynamic properties of Sr(POF(Sr-FAP) and Ca(POF(Ca-FAP) are systematically investigated by the first-principles calculations. The calculated electronic band structure indicates that the Sr-FAP and Ca-FAP are insulator materials with the indirect band gap of 5.273 eV and 5.592 eV, respectively. The elastic constants are obtained by the “stress–strain” method, and elastic modulus are further evaluated and discussed. The vibrational properties, including the phonon dispersion curves, the phonon density of states, the Born effective charge, and associated longitudinal optical and transverse optical (LO–TO) splitting of optical modes, as well as the phonon frequencies at zone-center are obtained within the linear-response approach. Substitution of Ca by Sr causes phonon frequencies to shift to lower values as expected due to the mass effect. Additionally, some phonon-related thermodynamic properties, such as Helmholtz free energy F, internal energy E, entropy S, and specific heat of Sr-FAP and Ca-FAP are predicted with the harmonic approximation. The present calculated results of two apatites are consistent with the reported experimental and theoretical results. [ABSTRACT FROM AUTHOR]

We present a first-principles study of the structural, dielectric, and lattice dynamical properties for chalcopyrite semiconductor ZnSnP2. The structural properties are calculated using a plane-wave pseudopotential method of density-functional theory. A linear response theory is used to derive Born effective charge tensors for each atom, dielectric constants in low and high frequency limits, and phonon frequencies. We calculate all zone-center phonon modes, identify Raman and infrared active modes, and report LO–TO splitting of the infrared modes. The results show an excellent agreement with experiment and propose several predictive behaviors. [ABSTRACT FROM AUTHOR]

An ab initio calculations on the ground and low-lying excited states (X2Σ+, 22Σ+, 32Σ+, 14Π, 24Π, 14Σ+, 24Σ+, and 34Σ+) of KBe molecule have been performed using multireference configuration interaction (MRCI) plus Davidson corrections (MRCI+Q) approach with all electron basis set aug-cc-pCV5Z-DK for Be and def2-AQZVPP-JKFI for K. The 32Σ+, 14Π, 24Π, 14Σ+, 24Σ+, and 34Σ+ states are investigated for the first time. Inner shell electron correlations are computed on the potential energy curves (PECs) calculations. The spectroscopic and molecular parameters are also predicted. In addition, The transition properties including transition dipole moment, Franck–Condon factors qυ′υ″, Einstein coefficients Aυ′υ″, and the radiative lifetimes τυ′ for the , , and transitions are predicted at the same time. [ABSTRACT FROM AUTHOR]

This paper performs the two-dimensional, soft-sphere molecular dynamics simulations to study the granular segregation in a binary granular mixture with the same size but different density in the container with the sawtooth base under horizontal vibration. The segregation phase diagram is presented in the acceleration-frequency space. When the acceleration is high enough to result in relative motions of the particles, the system can be in various states (mixed state, vertical and horizontal segregation state), which depend on both acceleration and frequency. Due to the sawtooth base there is stratified flow effect besides density effect. The density effect raises the light particles. The stratified flow drives the particles in the upper levels to the right and the particles in the lower particles to the left, resulting in the appearance of the left segregation state. The left segregation state can be changed to the right segregation by changing the shape of the sawtooth. As the vibration frequency increases, the stratified flow effect becomes weaker and weaker, so at high vibration frequencies the vertical segregation state appears instead of the left segregation state. [ABSTRACT FROM AUTHOR]