Sökning: "First-Principles"

Visar resultat 11 - 15 av 281 avhandlingar innehållade ordet First-Principles.

1. 11. High Resolution Tip-Enhanced Raman Images of Single Molecules from First Principles Simulations

   Författare :Zhen Xie; Yi Luo; Filippo De Angelis; KTH; []
   Nyckelord :First Principles; Tip-Enhanced Raman Images; light-matter interactions at the nanoscale; Teoretisk kemi och biologi; Theoretical Chemistry and Biology;

   Sammanfattning : With the precise control of spatially confined plasmon (SCP), tip-enhanced Raman spectroscopy (TERS) has achieved sub-nanometer resolution, leading to the chemical and physical characterization of the single molecule by optical Raman images. In the high resolution TERS measurements, the SCP spatial distribution generates the position-dependent Raman images. LÄS MER

3. 12. 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

4. 13. Point defects and ion conduction in solid oxides: a first-principles case study of La2Zr2O7

   Författare :Joakim Nyman; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; proton; self compensation; hydrogen economy; DFT; La2Zr2O7; acceptor doping; lanthanum zirconate; oxygen vacancy; SOFC; pyrochlore; point defect; trapping; computational methods; solid oxide; charge compensation; first principles; ion conduction; solid oxide fuel cell; ceramic electrolyte; defect cluster; fuel cell; hydrogen;

   Sammanfattning : In the endeavor to attain a clean environment and sustainable energy consumption, the notion of a future hydrogen economy stands out as one of the grandest visions. Striving for this vision, a critical task lies in optimizing the performance of the fuel-cell devices responsible for extracting electric power from the energy stored in hydrogen molecules. LÄS MER

5. 14. First-Principles Studies of Materials Properties : Pressure-Induced Phase Transitions & Functional Materials

   Författare :Thanayut Kaewmaraya; Rajeev Ahuja; Scheicher Ralph; Naurang Saini; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Density functional theory; Pressure-induced phase transitions; Ab-initio molecular dynamic; hybrid functional; Ab-initio random structure searching; Phase change material; 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 first-principles studies of materials properties within the framework of the density functional theory (DFT). The thesis constitutes three main parts, i. e., pressure-induced phase transitions in solids, data-storage and clean-energy materials. LÄS MER

7. 15. First-principles investigations of planar defects

   Författare :Lu Song; Levente Vitos; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : Two types of planar defects, phase interface and stacking fault, are addressed in this thesis. The investigation is mainly carried out for stainless steels which are fundamental materials in modern society. For the phase interface, we investigate the metallic bcc/bcc and fcc/bcc phase interfaces. LÄS MER