Sökning: "Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik"

Visar resultat 36 - 40 av 84 avhandlingar innehållade orden Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik.

  1. 36. Theoretical studies of a nanoparticle bridge platform for molecular electronics measurements

    Författare :Henrik Löfås; Rajeev Ahuja; Jan Isberg; Anton Grigoriev; Gemma Solomon; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : The main focus of this thesis is the theoretical investigations of a nanogap platform used for molecular electronics measurements under ambient conditions. The nanogap is about 20 nm wide, while the molecules investigated here (octanethiol(OT) and octanedithiol(ODT)) are about 1-1.5 nm long making it impossible to bridge the gap with one molecule. LÄS MER

  2. 37. 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

  3. 38. Computational Studies of Hydrogen Storage Materials : Physisorbed and Chemisorbed  Systems

    Författare :Pornjuk Srepusharawoot; Rajeev Ahuja; Puru Jena; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Density functional theory; Ab initio molecular dynamics; Ab initio random structure searching; Hydrogen storage materials; Alkaline earth dicarbide; Condensed matter physics; Kondenserade materiens fysik; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : This thesis deals with first-principles calculations based on density functional theory to investigate hydrogen storage related properties in various high-surface area materials and the ground state crystal structures in alkaline earth dicarbide systems. High-surface area materials have been shown to be very promising for hydrogen storage applications owing to them containing numerous hydrogen adsorption sites and good kinetics for adsorption/desorption. LÄS MER

  4. 39. Free Metal Clusters Studied by Photoelectron Spectroscopy

    Författare :Tomas Andersson; Olle Björneholm; Maxim Tchaplyguine; Paolo Piseri; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; clusters; nanoparticles; electronic structure; photoelectron spectroscopy; synchrotron radiation; surface segregation; nanoalloys; size-dependence; metallicity; plasmons; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : Clusters are aggregates of a finite number of atoms or molecules. In the present work, free clusters out of metallic parent materials have been created and studied by synchrotron radiation-based photoelectron spectroscopy. The clusters have been formed and studied in a beam and the electronic structure of the clusters has been investigated. LÄS MER

  5. 40. Insights into Materials Properties from Ab Initio Theory : Diffusion, Adsorption, Catalysis & Structure

    Författare :Andreas Blomqvist; Rajeev Ahuja; Christopher Wolverton; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Density functional theory; Molecular dynamics; Diffusion; Catalysis; Adsorption; Random structure search; Hydrogen-storage materials; Phase-change materials; Defects and diffusion; Defekter och diffusion; Surfaces and interfaces; Ytor och mellanytor; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : In this thesis, density functional theory (DFT) calculations and DFT based ab initio molecular dynamics simulations have been employed in order to gain insights into materials properties like diffusion, adsorption, catalysis, and structure. In transition metals, absorbed hydrogen atoms self-trap due to localization of metal d-electrons. LÄS MER