Sökning: "Ab initio"

Visar resultat 1 - 5 av 305 avhandlingar innehållade orden Ab initio.

  1. 1. Ab initio Lattice Dynamics : Hydrogen-dense and Other Materials

    Författare :Duck Young Kim; Rajeev Ahuja; Richard Needs; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; Density functional theory; Density functional perturbation theory; Hydrogen-dense materials; Phase transition; High pressure; Ab initio lattice dynamics; Superconductivity; Quasi-particle approximation; Physics; Fysik;

    Sammanfattning : This thesis presents a theoretical study of materials under high pressure using ab initio lattice dynamics based on density functional theory and density functional perturbation theory using both super-cell and linear response approach. Ab initio lattice dynamics using super-cell approach is applied to compare our theoretical predictions with experimental findings. LÄS MER

  2. 2. Molecular Electronics : Insight from Ab-Initio Transport Simulations

    Författare :Jariyanee Prasongkit; Rajeev Ahuja; Magnus Paulsson; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Molecular Electronics; Ab Initio; DNA Sequencing; Nanoscience; Graphene; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : This thesis presents the theoretical studies of electronic transport in molecular electronic devices. Such devices have been proposed and investigated as a promising new approach that complements conventional silicon-based electronics. LÄS MER

  3. 3. Defects and Impurities in CdTe : An ab Initio Study

    Författare :Anna Lindström; Mattias Klintenerg; Susanne Mirbt; Biplab Sanyal; Peter Zahn; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Native defects; Compensation mechanisms; Semiconductor doping; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : In this thesis defects and impurities in CdTe have been studied with ab initio methods. CdTe is a II-VI semiconductor with many important applications such as γ- and X-ray detectors, solar cells and medical imaging. LÄS MER

  4. 4. 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 :NATURAL SCIENCES; NATURVETENSKAP; 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

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

    Författare :Weimin Cao; Seshadri Seetharaman; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; 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