Visar resultat 1 - 5 av 551 avhandlingar innehållade ordet DENSITY-FUNCTIONAL-THEORY.

  1. 1. Manganese and Iron Heterodimers and Homodimers in Enzymes : Insights from Density Functional Theory

    Författare :Katarina Roos; Per Siegbahn; Margareta R. A. Blomberg; Frank Neese; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; NATURAL SCIENCES; Ribonucleotide reductase; manganese; iron; density functional theory; kemisk fysik; Chemical Physics;

    Sammanfattning : The enzyme ribonucleotide reductase (RNR) catalyzes the reduction of ribonucleotides to deoxyribonucleotides, the building blocks of DNA, and is essential for all organisms. Canonical class I RNR R2 proteins use a diiron cofactor to generate a tyrosyl radical, which is required for catalysis. LÄS MER

  2. 2. Challenges in Enzyme Catalysis - Photosystem II and Orotidine Decarboxylase : A Density Functional Theory Treatment

    Författare :Marcus Lundberg; Margareta Blomberg; Per Siegbahn; Jeremy Harvey; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; photosystem II; oxyl radical; manganese systems; orotidine decarboxylase; reaction mechanism; density functional theory; Quantum chemistry; Kvantkemi;

    Sammanfattning : Possibly the most fascinating biochemical mechanism remaining to be solved is the formation of oxygen from water in photosystem II. This is a critical part of the photosynthetic reaction that makes solar energy accessible to living organisms. LÄS MER

  3. 3. Applied density functional theory : calculating structures and energies on ribonucleotide reductase and polycyclic aromatic hydrocarbons

    Författare :Kyung-Bin Cho; Stockholms universitet; []

    Sammanfattning : .... LÄS MER

  4. 4. Nonlocal Correlations in Density Functional Theory

    Författare :Henrik Rydberg; Chalmers University of Technology; []
    Nyckelord :bonding; GGA; adhesion; graphene; DFT; exchange; adsorption; LDA; first principles; polarization; vdW; determinants; correlation; graphite; surface states; van der Waals; density-functional theory; physisorption; nonlocal; functional;

    Sammanfattning : In Density Functional Theory, the widely used local and semilocal approximations to the exchange-correlation energy, the local density approximation (LDA) and the generalized gradient approximations (GGAs), lack a physical description of truly nonlocal correlation effects, which are absolutely essential for a proper description of soft matter. A scheme is proposed that provides a basis for systematic improvements beyond LDA and GGA, including correlations at intermediate and long range, giving rise to bonds of pure van der Waals type as well as more intricate, intermediate-range correlation bonds. LÄS MER

  5. 5. Density Functional Theory in Computational Materials Science

    Författare :Jorge Mario Osorio Guillén; Rajeev Ahuja; Börje Johansson; Bruce N. Harmon; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; Physics; Density Functional Theory; High Pressure; Phase Transitions; Elastic Properties; Lithium Batteries; Dilute Magnetic Semiconductors; Fysik; Physics; Fysik;

    Sammanfattning : The present thesis is concerned to the application of first-principles self-consistent total-energy calculations within the density functional theory on different topics in materials science. Crystallographic phase-transitions under high-pressure has been study for TiO2, FeI2, Fe3O4, Ti, the heavy alkali metals Cs and Rb, and C3N4. LÄS MER