The optical properties of GaAs(110) and GaP(110) surfaces are studied by means self-consistent local-density calculations. A very large contribution to the reflectance anisotropy is found be related transitions which do not involve surface states. These give a substantial---yet smaller---contribution also differential reflectivity. Comparison made with relevant experimental data.

The strength of electronic correlation effects in the spin-dependent structure ferromagnetic bcc Fe(110) has been investigated by means spin and angle-resolved photoemission spectroscopy. experimental results are compared to theoretical calculations within three-body scattering approximation dynamical mean-field theory, together with one-step model process. This comparison indicates that present state art many-body calculations, although improving description Fe, give too small mass...

The electronic properties of an Sb overlayer deposited onto a GaAs(110) surface have been calculated using self-consistent-pseudopotential approach and assuming the ordered-overlayer geometry proposed in recent low-energy electron diffraction studies. results show that adatoms are bound by strong covalent bonds to substrate various or chemisorption-induced states appear throughout valence band. Comparison with photoemission data allows us assign major Sb-induced structure appearing energy...

A self-consistent pseudopotential approach has been used to calculate the electronic structure of GaP(110) surface in both ideal and relaxed configurations. Calculations have performed using repeated slab method a local form bare ionic pseudopotential. An efficient procedure, which allows us obtain quick convergence eliminates some difficulties found previous applications method, used. Particular care devoted complete consistency between bulk calculations. Our results for show various...

The role of self-consistency and the atomic distortions in determining electronic structure cleavage surfaces GaAs ZnSe has been investigated using layer method an iterative tight-binding approach, which takes account difference between surface bulk configurations. Several bands resonances are identified near gaps empty lenses projected band-structure their sensitivity to modifications potential discussed. In case inclusion at is essential order obtain theoretical results reasonable...

We have investigated the spin-dependent quasiparticle lifetimes and strength of electron correlation effects in ferromagnetic 3$d$ transition metals Fe, Co, Ni by means spin- angle-resolved photoemission spectroscopy. The experimental data are accompanied state-of-the-art many-body calculations within dynamical mean-field theory three-body scattering approximation, including fully relativistic process one-step model. Our quantitative analysis reveals that inclusion local Coulomb interactions...

We study the energy spectra of small three-dimensional (3D) and two-dimensional (2D) semiconductor quantum dots through different theoretical approaches (single-site Hubbard Hartree-Fock hamiltonians); in smallest we also compare with exact results. find that purely 2D models often lead to an inadequate description Coulomb interaction existing realistic structures, as a consequence overestimated carrier localization. show dimensionality has crucial impact on (i) accuracy predicted addition...

We report the inclusion of electron-electron correlation in calculation transport properties within an ab initio scheme. A key step is reformulation Landauer's approach terms effective transmittance for interacting electron system. apply this framework to analyze effect short-range interactions on Pt atomic wires and discuss coherent incoherent correction mean-field approach.

Experimental angle-integrated photoemission curves taken on Cl-covered (110) surfaces of GaAs, GaSb, and InSb have been compared to tight-binding calculations the local density states. The results clearly demonstrate that Cl adatoms are bound anion substrate atoms rather than cation atoms. Some qualitative information is also provided surface relaxation chemisorption bond lengths.

We demonstrate that the Hubbard correlation among Ni $3d$ electrons is able to reproduce insulating character of NiO, correct value gap, orbital valence band edge, and presence satellite structures. have determined quasiparticle spectra starting from complex single particle structure NiO including on-site repulsion according a recently developed three-body scattering theory which allows us treat highly correlated hybridized systems. The calculated in excellent agreement with photoemission data.

A fully self-consistent pseudopotential calculation of the electronic properties atomic hydrogen chemisorbed on GaAs and GaP(110) surfaces is reported. Different chemisorption geometries substrate coverages are considered. The results compared with experimental information to select a structural model.

We have measured the energy distribution curves of photoelectrons ($h\ensuremath{\nu}=21.2$ eV) from a Zn single-crystal (0001) face covered by an ordered Cu monolayer and bulk Cu. found narrow (2.3-eV total width) $d$-state peak 1.20 eV below position $3d$ structure. also calculated density states for both on unsupported monolayer. Theory is in good agreement with experiments. The overlayer shown to be very similar that atomic layer.

We present excitation energy spectra of few-electron vertically coupled quantum dots for strong and intermediate inter-dot coupling. By applying a magnetic field, we induce ground state transitions identify the corresponding numbers by comparison with few-body calculations. In addition to atomic-like states, find novel "molecular-like" phases. The isospin index characterizes nature bond artificial molecule this control. Like spin in single dot, leading full polarization are observed increasing field.

We present the first time-dependent density functional theory (TDDFT) calculation on a light-harvesting triad carotenoid−diaryl-porphyrin−C60. Besides numerical challenge that ab initio study of electronic structure such large system presents, we show TDDFT is able to provide an accurate description excited-state properties system. In particular, calculate photoabsorption spectrum supramolecular assembly, and interpretation photoexcitation mechanism in terms component moieties. The good...

We report on a quantitative investigation of the spin-dependent quasiparticle lifetimes and electron correlation effects in ferromagnetic hcp Co(0001) by means spin- angle-resolved photoemission spectroscopies. The experimental spectra are compared detail to state-of-the-art many-body calculations within dynamical mean-field theory three-body scattering approximation, including full calculation one-step process. From this comparison we conclude that although strong local Coulomb interactions...

In order to provide a structural basis for physical understanding of exchange bias in metal/magnetic-oxide interfaces, we have determined the structure Fe/NiO(001) interface by means x-ray absorption spectroscopy and ab initio density functional theory calculations. A Fe-Ni alloyed phase on top an interfacial FeO planar layer is formed. The exhibits 7% expanded interlayer distance 0.3 buckling; its presence predicted increase spin magnetic moment Fe atoms 0.6 mu(B), compared ideally abrupt interface.

We present the results of self-consistent band-structure calculations for bulk GaAs, in which density-functional theory is applied with a nonlocal expression exchange and correlation energy, ${E}_{\mathrm{xc}}[n(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})]$. Using same ionic potentials basis set, other local expressions are also considered comparison. It will be shown that inclusion nonlocality potential improves description valence bands, but does not solve "gap problem" experienced by...

We present the results of an ab initio characterization electronic and magnetic properties ${\mathrm{Cr}}_{8}$ molecular ring. The original molecule with formula $[{\mathrm{Cr}}_{8}{\mathrm{F}}_{8}{\mathrm{Piv}}_{16}]$($\mathrm{HPiv}$=pivalic acid, trimethyl acetic acid) has been approximated by replacing disordered methyl groups H atoms, obtaining de facto $[{\mathrm{Cr}}_{8}{\mathrm{F}}_{8}({\mathrm{O}}_{2}\mathrm{CH}{)}_{16}]$. find in agreement experiments that Cr atoms attain a local...

The role of on-site correlation in the low-energy excitations nickel is studied by comparing results high-angular and high-energy resolution photoemission spectroscopy with quasiparticle states calculated as a three-body scattering solution multiorbital Hubbard model. It found that effects modify energy dispersion spin polarization electron are essential order to get quantitative agreement experimental data.

The low-energy electronic excitations in cobalt are studied by a theoretical method that includes many-body effects and realistic description of the band structure. Angle-resolved photoemission spectra measured on thick film hexagonal close-packed Co Cu(111) agree well with calculated spectral functions. Because no sharp quasiparticle peaks exist for binding energies larger than 2 eV this energy region spectrum is essentially incoherent. corrections much stronger majority-spin channel...

We report about the inclusion of many-body electron interactions in simulation transport properties. derive a general Landauer-like expression for current, valid also case conductors which charge carriers undergo generic scattering processes. An important focus is put on derivation theoretical framework, both formalism and actual implementation method, including treatment electronic correlation. then show an example application compare results conduction properties obtained with our new...

We have performed pseudopotential self-consistent band-structure calculations for bulk solids in the framework of Kohn-Sham density-functional theory, applying nonlocal exchange-correlation functional Gunnarsson and Jones to valence electrons with no further approximation. present our method together representative results GaAs Si, main interest being focused on single-particle energy eigenvalues gaps. An accurate comparison obtained this approach local-density-approximation is given. The...

Experimental and theoretical results are presented for Cu on an Ni(111) surface. Angle-integrated ultraviolet photoelectron spectroscopy (UPS) ($h\ensuremath{\nu}=21.2$ eV) given with increasing coverages $\ensuremath{\theta}$ from 0.1 to 4 monolayers. The at $\ensuremath{\theta}\ensuremath{\ll}1$ refer isolated adatoms those $1<\ensuremath{\theta}<4$ ordered overlayer. position line shape of the $3d$ peak same $0.1<\ensuremath{\theta}<1$: This indicates that main features band...

We present a method which allows to include narrow-band correlation effects into the description of both valence and core states we apply it prototypical case nickel. The results an ab-initio band calculation are used as input mean-field eigenstates for self-energy corrections spectral functions according three-body scattering solution multi-orbital Hubbard hamiltonian. calculated quasi-particle spectra show remarkable agreement with photoemission data in terms width, exchange splitting,...