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The crystal structure of Bi2Se3 using ab initio calculations have been investigated using density functional theory (DFT). According to the atomic positions provided by the previous literature, we were able to construct a lattice structure using visualization software Material Studio. This structure is found in rhombohedral, of the space group D53d with R3m (#166) and lattice parameter of a = b = 4.143 A, c = 28.836 A, and the bond angle of α = β = 90°, γ = 120°, while treating the exchange-correlation potential with the general gradient Approximations (GGA) method. The structural calculations were performed to investigate, the electronic, charge density, optical, and phonon properties. To conclude, the partial density of state plots indicates the material properties near to the fermi level determined by the p state orbitals.

WOS: 000355571800008, The absorption and fluorescence spectra of three 2-((phenylimino)methyl)phenol derivatives have been evaluated in a series of organic solvents. The ground state (mu(g)) and excited state (mu(e)) dipole moments are determined by means of Lippert-Mataga, Bakhshiev, Kaski-Chamma-Viallet and Reichardt solvatochromic shift methods based on the solvent polarity parameters. Excited state dipole moments are found as larger than the ground state dipole moment due to substantial redistribution of the pi-electron density in more polar excited state and thus resonance structures of 2-((phenylimino)methyl)phenol derivatives are analyzed. Solute-solvent interactions are analyzed by means of linear solvation energy relationships (LSER) using dielectric constant function f(epsilon), refractive index function f(n) and Kamlet-Taft parameters (H-bond donor ability, alpha and H-bond acceptor ability, beta). External electric field (EF) effect on HOMO-LUMO gap (HLG) and dipole moment are investigated by B3LYP, LDA and GGA methods. Density of states (DOS) and HOMO, LUMO plots are also investigated by the same methods, Bitlis Eren University, Scientific and Technological Application and Research Center; Bitlis Eren University Research Foundation [BEBAP-2014.05], The authors greatly acknowledge the support of Bitlis Eren University, Scientific and Technological Application and Research Center.; The authors greatly appreciate Bitlis Eren University Research Foundation for financial support. Project number: BEBAP-2014.05.

Electronic and magnetic properties of transition-metal oxides are a continuing research theme due to the variety of ground states and their technological applications. In the present paper, we present first-principles calculations using the full-potential linear augmented plane-wave methods (FP-LAPW) on the structural, electronic and magnetic properties of tree cubic (Pm–3m space group) perovskite oxides SrRuO3, BaRuO3, and CaRuO3 in comparison with other phases ((4H) four-layered hexagonal (P63/mmc space group), (2H) two-layered hexagonal (P63/mmc space group) and orthorhombic (Pnma space group). The current study is given within the density-functional theory basis DFT. The exchange-correlation potential is introduced by different approaches. We computed the equilibrium lattices, bulk modulus and its pressure derivatives and equilibrium volume. Our obtained results agree successfully with the theoretical and experimental data. The spin magnetic moments of these oxides have been obtained to investigate the magnetic properties. We report a detailed analysis of the different ground states properties for considerable oxides using GGA and GGA-modified Becke–Johnson computational approaches.

International audience; The overall large ionic character of MgH2 is reduced by inserting light elements from the first period, B and C, using a trirutile host superstructure. From DFT computations, both elements are found destabilizing to the structure with largely positive cohesive energy with interstitial B and slightly negative cohesive energy with interstitial C. This trend is also observed for low amounts of insertion down to (B,C)0.167MgH2. From the Bader charge analysis the largely ionic character of hydrogen is decreased to an average H−0.37 in the neighborhood of C and H−0.75 for the other hydrogen atoms (resp. H−0.64 and H−0.76 for B insertion). This peculiar behavior should enable enhancing the kinetics of H release for potential applications.

International audience; Stability of different phases of AMoO4 (A = Mg, Ni) molybdates versus A–O bonding and the corresponding electronic structures are examined from first principles. The energy-volume equations of state for three forms (β, α, ω), characterized by decreasing volumes in the sequence of Mg and Ni molybdates are established. While NiMoO4 is energy stabilized in the sequence β → α → ω, an opposite behavior is identified for the Mg molybdate. Charge analysis characterizing ionic Mg2+ versus covalent Ni+1.2 behaviors can explain the trend. Electronic band structure also shows large differences: MgMoO4 is insulating with a 2 eV band gap while in a magnetic state, NiMoO4 is a small gap (0.2 eV) semi-conductor. Chemical bonding properties show weak Mg and strong Ni bonding with oxygen, while identifying the Mo–O interaction as prevailing.

International audience; Within density functional theory the equations of state for perovskite (PV) and post-perovskite (PPV) forms of CaRhO3 are obtained with equilibrium values of volume in agreement with experiment. Energy magnitudes point to a stabilization of PPV versus PV. This is interpreted by analyses of the charge density and the chemical bonding plots, showing that the Rh–O interactions within two oxygen sublattices are selectively differentiated and reinforced for one of the two oxygen sublattices within PPV variety with respect to PV one. Investigation of the magnetic properties shows no magnetic order and a metallic character for PV while ferromagnetism occurs in PPV with a tendency to insulating behavior. This long range order is favored by direct t2g–t2g interactions through edge sharing octahedra in PPV CaRhO3, stronger than indirect t2g–pπ–t2g ones in PV variety.