Sökning: "ab-initio"

Visar resultat 6 - 10 av 329 avhandlingar innehållade ordet ab-initio.

  1. 6. Electronic structure and exchange interactions from ab initio theory : New perspectives and implementations

    Författare :Ramon Cardias Alves de Almeida; Olle Eriksson; Anders Bergman; Attila Szilva; R. B. Muniz; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ab initio; exchange interactions; non-collinear magnetism; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : In this thesis, the magnetic properties of several materials were investigated using first principle calculations. The ab initio method named real space linear muffin-tin orbitals atomic sphere approximation (RS-LMTO-ASA) was used to calculate the electronic structure and magnetic properties of bulk systems, surface and nanostructures adsorbed on surfaces. LÄS MER

  3. 7. Adsorption of surface active elements on the iron (100) surface : A study based on ab initio calculations

    Författare :Weimin Cao; Seshadri Seetharaman; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; sulfur; oxygen; surface adsorption; iron surface; ab initio calculations; adsorption energy; work function; difference charge density; thermodynamic stability; average velocity; Materials science; Teknisk materialvetenskap;

    Sammanfattning : In the present work, the structural, electronic properties, thermodynamic stability and adatom surface movements of oxygen and sulfur adsorption on the Fe surface were studied based on the ab initio method. Firstly, the oxygen adsorbed on the iron (100) surface is investigated at the three adsorption sites top, bridge and hollow sites, respectively. LÄS MER

  4. 8. Materials Design from ab initio Calculations

    Författare :Sa Li; Börje Johansson; Rajeev Ahuja; Gilles Hug; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; DFT; MAX; Optics; phase transition; phonon; EOS; Fysik; Physics; Fysik;

    Sammanfattning : This thesis presents a theoretical study of bulk materials using ab initio methods based on the density functional theory (DFT).Crystallographic structural phase transformations and phase stability for 5f-dioxides, ABO3 perovskites, and ABO4 compounds have been extensively studied. LÄS MER

  5. 9. The water molecule in gaseous, liquid and solid surroundings : an ab initio molecular dynamics study

    Författare :Lars Ojamäe; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : .... LÄS MER

  7. 10. Ab initio simulations of core level spectra : Towards an atomistic understanding of the dye-sensitized solar cell

    Författare :Ida Josefsson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; multiconfigurational quantum chemistry; CASSCF calculations; core-level spectroscopy; x-ray photoelectron spectroscopy; x-ray absorption; resonant x-ray scattering; dye solar cells; transition metals; kemisk fysik; Chemical Physics;

    Sammanfattning : The main focus of this thesis is ab initio modeling of core level spectra with a high-level quantum chemical description both of the chemical interactions and of local atomic multiplet effects. In particular, the combination of calculations and synchrotron-based core-level spectroscopy aims at understanding the local structure of the electronic valence in transition metal complexes, and the details of the solvation mechanisms of electrolyte solutions, systems relevant for the dye-sensitized solar cell. LÄS MER