Sökning: "kvantkemi"

Visar resultat 16 - 20 av 63 avhandlingar innehållade ordet kvantkemi.

  1. 16. Quantum Holonomies : Concepts and Applications to Quantum Computing and Interferometry

    Författare :David Kult; Erik Sjöqvist; Gunnar Björk; Barry Sanders; Uppsala universitet; []
    Nyckelord :Physics; Quantum Holonomy; Geometric Phase; Quantum Computation; Completely Positive Map; Mixed State; Interferometry; Fysik;

    Sammanfattning : Quantum holonomies are investigated in different contexts.A geometric phase is proposed for decomposition dependent evolution, where each component of a given decomposition of a mixed state evolves independently. It is shown that this geometric phase only depends on the path traversed in the space of decompositions. LÄS MER

  3. 17. Open Quantum Systems : Effects in Interferometry, Quantum Computation, and Adiabatic Evolution

    Författare :Johan Åberg; Erik Sjöqvist; Sten Lunell; Vlatko Vedral; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Open Systems; Completely Positive Maps; Channels; Decoherence; Quantum Information; Quantum Computing; Adiabatic Approximation; Quantum Search; Time-Complexity; Fysik; Physics; Fysik;

    Sammanfattning : The effects of open system evolution on single particle interferometry, quantum computation, and the adiabatic approximation are investigated.Single particle interferometry: Three concepts concerning completely positive maps (CPMs) and trace preserving CPMs (channels), named subspace preserving (SP) CPMs, subspace local channels, and gluing of CPMs, are introduced. LÄS MER

  4. 18. Theoretical studies on photophysics and photochemistry of DNA

    Författare :Yuejie Ai; Yi Luo; Lluís Blancafort; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Quantum chemistry; Kvantkemi; SRA - Molecular Bioscience; SRA - Molekylär biovetenskap;

    Sammanfattning : Theoretical studies on biological systems like nucleic acid and protein have been widely developed in the past 50 years and will continue to be a topic of interest in forefronts of natural science. In addition to experimental science, computational modeling can give useful information and help us to understand biochemical issues at molecular, atomic and even electronic levels. LÄS MER

  5. 19. New Approaches to Large-Scale Electronic Structure Calculations

    Författare :Francesco Aquilante; Beräkningskemi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Theoretical chemistry; orbital localization; electron correlation; analytic gradients; Cholesky decomposition; density fitting; quantum chemistry; Teoretisk kemi; kvantkemi;

    Sammanfattning : Recent years have witnessed a growing interest of the scientific community for the use of ab initio and density functional theory methods in theoretical studies of molecules containing many atoms. However, the `scaling wall' of some of the most accurate of such methods is often an obstacle for their applicability to systems of real-life interest, e. LÄS MER

  7. 20. Theoretical studies of mononuclear non-heme iron active sites

    Författare :Arianna Bassan; Per E. M. Siegbahn; Sason Shaik; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quantum chemistry; enzyme catalysis; iron enzymes; Quantum chemistry; Kvantkemi;

    Sammanfattning : The quantum chemical investigations presented in this thesis use hybrid density functional theory to shed light on the catalytic mechanisms of mononuclear non-heme iron oxygenases, accommodating a ferrous ion in their active sites. More specifically, the dioxygen activation process and the subsequent oxidative reactions in the following enzymes were studied: tetrahydrobiopterin-dependent hydroxylases, naphthalene 1,2-dioxygenase and α-ketoglutarate-dependent enzymes. LÄS MER