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Abstract: The adsorption of 0.25, 0.5 and 1 monolayer (ML) of the transition metal Ni on the metal substrate Al(110) was studied using first-principles calculations at the level of density functional theory. The metal–metal system was analyzed with the generalized gradient approximation. Four stable atomic configurations were considered, and the optimized geometries and adsorption energies of different Ni adsorption sites on the Al(110) surface at selected levels of coverage were calculated and compared. The four-fold hollow site was determined to be the most stable adsorption site with adsorption energy of 5.101eV at 0.25ML, 3.874eV at 0.5ML and 3.665eV at 1ML. The adsorption energies of the four sites slightly decreased as the Ni coverage increased. Work function analysis showed that when Ni is adsorbed on the Al(110) surface, the work function decreased as the coverage increased due to depolarization. The Mulliken population and density of states were calculated to determine the charge distribution of the adsorption site, confirming that a chemisorption interaction exists between the adsorbed Ni atom and Al(110) surface atoms. [Copyright &y& Elsevier]

Abstract: BC5 is a newly synthesized superhard material. We present a systematic investigation of optical properties of BC5 in P3m1 and I-4m2 phases at ambient and high pressure in the framework of density functional theory with the generalized gradient approximation (GGA) in this paper. Optical properties such as dielectric function, refractive index, absorption, reflectivity and electron energy-loss spectrum are obtained successfully. The feature in the spectra of the optical parameters is discussed. Through calculation, we find BC5 is optically anisotropic. Moreover, the dielectric function exhibits a large change at 70GPa pressure for P3m1 BC5 phase, but I-4m2 phase not, indicating the stable electronic structure that the I-4m2 phase possesses. [Copyright &y& Elsevier]

Abstract: A systematic theoretical study is presented for the structural and electronic properties of HfB2 with AlB2 structure under pressure ranging from 0 to 240GPa in the framework of density functional theory. The results at zero pressure are in good agreement with the available theoretical and experimental values. The pressure dependence of structural property shows that the effect of pressure is little on the structure of HfB2. The density of states (DOS) of HfB2 versus pressure is also successfully calculated. We find high pressure greatly changes the profile of the DOS, but it hardly changes the DOS value at Fermi level. Meanwhile, the Mulliken population analyses are investigated. It is suggested that as the pressure increases, a number of charge transfer from Hf to B atoms. [Copyright &y& Elsevier]

Abstract: The elastic constants of B1- and B2-type MgO and SrO are calculated by a first-principles method at ambient condition. For B1-type MgO and SrO, the dependence of the elastic constants, the bulk modulus B, the shear constants c S and the Cauchy relation on the applied pressure are presented. The calculated results agree quite well with the comparable experimental data and the values of other works. Moreover, the thermodynamic properties (Debye temperature, melting temperature) and sound velocity is investigated under high pressure for the first time. [Copyright &y& Elsevier]

Using first-principles methods, we investigated the effect of structural deformation on the electronic and magnetic properties of Sr 3 Ir 2 O 7 by two tuning ways: reducing only the interlayer spacing and the uniaxial-like compression. In both cases, an insulator-metal transition is successfully achieved with significantly different Fermi surface features. The former consists of a hole pocket and an electronic pocket, while for the latter, a pseudo-gap is captured near the center of the crystallographic Brillouin zone. The anti-ferromagnetism collapses completely and is not fully synchronized with the closing of the Mott gap in two kinds of compression cases, indicating that the conventional correlation between magnetic order and Mott insulating state does not exist here. Our research is conducive to understand the nature of lattice distortion-induced electronic and magnetic transitions, and will be expected to provide a new theoretical reference for the experimental regulation of novel metallic properties in iridium. [ABSTRACT FROM AUTHOR]

Abstract: The equations of state (EOS) and other thermodynamic properties of TiB2 are investigated using ab initio plane-wave pseudopotential density functional theory method. The obtained results are in good agreement with the experimental measured data and other theoretical calculated ones. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the dependences of relative volume V/V 0 on pressure P, cell volume V on temperature T, and Debye temperature Θ and specific heat C V on pressure P are successfully obtained. [Copyright &y& Elsevier]

Using first-principles calculations, we investigate the effects of two kinds of oxygen defects on the electronic and magnetic properties in SrIrO 3 bulk. One is the oxygen defect in IrO 2 plane (Ov1) and the other out-of-plane (Ov2). The results show that both oxygen defects enhance the inherent metallicity of the crystal and there is no tendency to achieve the Mott transition. Most surprised, we find that a small out-of-plane magnetic moment along c axis is formed due to the apical tilting of the defective octahedrons induced by the in-plane oxygen defects. While a local and weak ab in-plane ferromagnetic response comes from the out-of-plane defect which destroys the connectivity between adjacent layers and promotes a small in-plane rotation. In addition to the distortion of the defective blocks, the weak ferromagnetic phenomenon is also limited by the concentration of oxygen defects. Our research indicates that non-equivalent oxygen deficiencies exert distinct regulatory roles on the magnetic properties. [ABSTRACT FROM AUTHOR]