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Articles you may be interested inElectronic structure and optical conductivity of two dimensional (2D) MoS2: Pseudopotential DFT versus full potential calculations AIP Conf.A systematic density functional theory study of the electronic structure of bulk and (001) surface of transitionmetals carbides The structure, energetics, and nature of the chemical bonding of phenylthiol adsorbed on the Au(111) surface: Implications for density-functional calculations of molecular-electronic conduction J. Chem. Phys. 122, 094708 (2005); 10.1063/1.1850455 Study with density functional theory method on methane dehydro-aromatization over Mo/HZSM-5 catalysts I: Optimization of active Mo species bonded to ZSM-5 zeolite A density functional theory study of site-specific methyl reaction on MoO 3 (010) : The effects of methyl coverageWe report extensive density functional theory calculations, using pseudopotentials with a plane-wave basis, for the properties of the ͑010͒ face of molybdenum trioxide (␣-MoO 3 ). The surface is modeled by a one-layer slab. Calculated bond lengths compare favorably with experimental measurements. The bonding of the different oxygen species to molybdenum is analyzed using the crystal orbital overlap population. This analysis indicates that the bonding is a combination of ionic and covalent character for all oxygen species. The terminal oxygen exhibits covalent bonding to Mo which is stronger than either of the two bridging oxygens. We also study the adsorption of hydrogen on this surface. Hydrogen is most strongly adsorbed over the terminal oxygen, followed by the asymmetric bridging oxygen, and then the symmetric bridging oxygen. This trend is explained in terms of simple chemical concepts. The inclusion of full surface relaxation is important for even a qualitative description of adsorbate bonding.

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We report interesting anomalies in the temperature dependent Raman spectra of FeSe 0.82 measured from 3K to 300K in the spectral range from 60 to 1800 cm -1 and determine their origin using complementary first-principles density functional calculations. A phonon mode near 100 cm -1 exhibits a sharp increase by ~ 5% in frequency below a temperature T s (~ 100K) attributed to strong spin-phonon coupling and onset of shortrange antiferromagnetic order. In addition, two high frequency modes are observed at 1350 cm -1 and 1600 cm -1 , attributed to electronic Raman scattering from (x 2 -y 2 )to xz / yz d-orbitals of Fe.

Molecular dynamics simulations were carried out to investigate the mechanical properties of silicon nanoparticles during uniaxial compression by a flat-punch indenter. We considered a large set of systems, with dimensions in the range 10 nm to 50 nm, and various shapes like cubic (perfect and blunt), spherical, truncated spherical, and Wulff-shaped, as well as two compression orientations and two temperatures. Thorough analyses of the simulations first revealed that the relation between nanoparticle size and strength, usually termed as 'smaller is stronger', is critically dependent on the nanoparticle shape, at least for the investigated size range. For instance, a significant and size-dependent strength decrease is determined for facetted Wulff-like nanoparticles, but not for cubic or spherical systems for compression along <100>. We also found that the nanoparticle shape greatly influences plasticity. Several original plasticity mechanisms are obtained, among which the nucleation of half-loop V-shaped dislocation contained in two different {111} planes, dislocations gliding in unusual {110} planes, or the nucleation of partial dislocations in shuffle {111} planes. Our investigations suggest that plasticity properties are mainly governed by the localization of shear stress build up during elastic loading, and the geometry of surfaces in contact with indenters, these two characteristics being intimately related to the nanoparticle shape.