Sökning: "First principles calculations"

Visar resultat 1 - 5 av 196 avhandlingar innehållade orden First principles calculations.

1. 1. Polar molecules in crystalline and surface environments : From first principles

   Författare :Maria Alfredsson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemistry; Kemi; Chemistry; Kemi; Inorganic Chemistry; oorganisk kemi;

   Sammanfattning : With the knowledge of the composition and structure of a chemical system, be it a molecule, a two-dimensional surface or a three-dimensional crystal, it is now possible to predict the specific properties of the compound under consideration via computational studies. Molecular and periodic Hartree-Fock and DFT calculations have been used as a tool to study polar molecules and how their properties respond to the molecular environment in a crystal or on an ionic surface. LÄS MER

3. 2. Catalytic Water Production from First-Principles Calculations

   Författare :Gustav Karlberg; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; platinum; Monte Carlo; first-principles; hydroxyl; transition metals; density functional theory DFT ; Metropolis; oxygen; water; water production reaction; hydrogen;

   Sammanfattning : The main subject of this thesis is the catalytic water production reaction on metal surfaces. This reaction is of great current interest due to its importance in fuel cells, a clean and efficient way to convert chemical energy into electrical. LÄS MER

4. 3. Effects of disorder in metallic systems from First-Principles calculations

   Författare :Christian Asker; Igor Abrikosov; Jörg Neugebauer; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Iron; Nickel; Magnesium; Manganese; Molybdenum; Zirconium; Elastic Constants; High pressure; Earth s core; Density-functional theory; Ab-initio; First-Principles; Core-level shifts; Molecular Dynamics; Phonons; Dynamical Instability; Condensed matter physics; Kondenserade materiens fysik; Computational physics; Beräkningsfysik;

   Sammanfattning : In this thesis, quantum-mechanical calculations within density-functional theory on metallic systems are presented. The overarching goal has been to investigate effects of disorder. In particular, one of the properties investigated is the bindingenergy shifts for core electrons in binary alloys using different theoretical methods. LÄS MER

5. 4. First-principles calculations of polymer interactions

   Författare :Jesper Kleis; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; polymer structure; polyvinylchloride.; polypropylene; polyethylene; sparse material systems; Density functional theory; polymer interactions; van der Waals interaction; polymer crystal; soft matter; DFT;

   Sammanfattning : This thesis reports on studies of interactions in sparse matter by first-principles calculations, in particular polymeric systems. The focus is on the three unbranched simple polymers: polyethylene (PE), isotactic polypropylene (PP) and isotactic polyvinylchloride (PVC), which together represent an important class of materials that form complexes stabilized by weak but long-range dispersive interactions. LÄS MER

7. 5. Structural and magnetic disorder in crystalline materials : a first principles study

   Författare :Davide Gambino; Björn Alling; Pavel Korzhavyi; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Disorder in crystalline materials can take different forms and originate from different sources. In particular, temperature introduces disorder in any kind of material. LÄS MER