Riad Shaltaf

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ABINIT [1] allows one to study, from first principles, systems made of electrons and nuclei (e.g. periodic solids, molecules, nanostructures, ...), on the basis of Density Functional Theory (DFT) and Many-Body Perturbation Theory. Beyond the computation of the total energy, charge density and electronic structure of such systems, ABINIT also implements many(More)
We use many-body perturbation theory, the state-of-the-art method for band-gap calculations, to compute the band offsets at the Si/SiO2 interface. We examine the adequacy of the usual approximations in this context. We show that (i) the separate treatment of band structure and potential lineup contributions, the latter being evaluated within(More)
The surface stress and energetics of the clean-, Sb-adsorbed-, and Sb-interdiffused-Geð001Þ surfaces have been calculated using the ab initio density functional method. It is found that interdiffusion of Sb into deeper layers of Geð001Þ leads to a more isotropic surface stress but corresponds to a higher total energy configuration. As a result of(More)
Ș. Ellialtıoğlu,1,* E. Mete,1,† R. Shaltaf,1 K. Allakhverdiev,2,3 F. Gashimzade,2 M. Nizametdinova,4 and G. Orudzhev4 1Department of Physics, Middle East Technical University, Ankara 06531, Turkey 2Institute of Physics, Azerbaijan National Academy of Sciences, Baku 370073, Azerbaijan 3Materials Institute, Marmara Research Center, TÜBİTAK, Gebze/Kocaeli,(More)
We have investigated Rb adsorption on the Si(100) surface for 0.5 and 1 monolayer coverages using the total energy method with norm-conserving pseudopotentials. For 2 · 1 reconstruction at 1 ML coverage symmetrized dimers are found to be energetically more favorable. On the other hand, half a ML coverage is found to have symmetrical dimers only for the most(More)
First-principles calculations using density functional theory based on norm-conserving pseudopotentials have been performed to investigate the Cs adsorption on the Si 001 surface for 0.5 and 1 ML coverages. We found that the saturation coverage corresponds to 1 ML adsorption with two Cs atoms occupying the double layer model sites. While the energy bands(More)
Using first-principles calculations based on density functional theory, we study the properties of germanium telluride crystalline nanoplatelets and nanoparticles. Above a diameter of 2.7 nm, we predict the appearance of polarization vortices giving rise to an unusual ferrotoroidic ground state with a spontaneous and reversible toroidal moment of(More)
First-principles calculations using density functional theory based on norm-conserving pseudopotentials have been performed to investigate the Mg adsorption on the Si~001! surface for 1/4, 1/2, and 1 monolayer ~ML! coverages. For both 1/4 and 1/2 ML coverages it has been found that the most favorable site for the Mg adsorption is the cave site between two(More)
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