Sökning: "Ab Initio Calculations"

Visar resultat 1 - 5 av 216 avhandlingar innehållade orden Ab Initio Calculations.

1. 1. 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

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

   Författare :Duck Young Kim; Rajeev Ahuja; Richard Needs; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; 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

4. 3. 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. 4. Density Functional Theory Calculations for Graphene-based Gas Sensor Technology

   Författare :Karim Elgammal; Anna Delin; Giuseppe Iannaccone; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; graphene; ab-initio; humidity; carbon dioxide; substrate; DFT; vdW; first-principle; simulation; calculations; Fysik; Physics;

   Sammanfattning : Nowadays, electronic devices span a diverse pool of applications, especially when getting smaller and smaller satisfying the more than Moore paradigm. To further develop this, studies focusing on material design toward electronic devices are crucial. LÄS MER

7. 5. Defects and Impurities in CdTe : An ab Initio Study

   Författare :Anna Lindström; Mattias Klintenerg; Susanne Mirbt; Biplab Sanyal; Peter Zahn; Uppsala universitet; []
   Nyckelord :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