Search for dissertations about: "Quantum chemistry"

Showing result 21 - 25 of 360 swedish dissertations containing the words Quantum chemistry.

  2. 21. Matrix Algebra for Quantum Chemistry

    Author : Emanuel H. Rubensson; Pawel Salek; Stefan Goedecker; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; linear scaling; reduced complexity; electronic structure; density functional theory; Hartree-Fock; density matrix purification; congruence transformation; inverse factorization; eigenvalues; eigenvectors; numerical linear algebra; occupied subspace; canonical angles; invariant subspace; Theoretical chemistry; Teoretisk kemi;

    Abstract : This thesis concerns methods of reduced complexity for electronic structure calculations.  When quantum chemistry methods are applied to large systems, it is important to optimally use computer resources and only store data and perform operations that contribute to the overall accuracy. READ MORE

  4. 22. ZnO Quantum Dots : Size Dependent Optical, Vibrational and Photoelectrochemical Properties

    Author : Jesper Jacobsson; Tomas Edvinsson; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; ZnO; nanoparticels; quantum dots; Chemistry with specialization in Inorganic Chemistry; Kemi med inriktning mot oorganisk kemi;

    Abstract : This thesis is devoted to quantum dots of ZnO in the size regime 2.5-10 nm.The focus is directed towards their size dependent properties with specialemphasis on the optical, vibrational and photocatalytic properties. The particleswere synthesized by hydrolysis in alkaline zinc acetate solution. READ MORE

  5. 23. Quantum Chemical Exploration of Nitriles in Prebiotic Chemistry and Astrobiology

    Author : Hilda Sandström; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; metadynamics; astrochemistry; iminoacetonitrile; hydrogen cyanide; acrylonitrile; azotosome; Titan;

    Abstract : The Universe hosts countless different chemical environments, such as planets, moons, comets and the interstellar medium. The diverse pressures, temperatures and chemical compositions of these environments make a wide variety of processes possible. READ MORE

  6. 24. Quantum Chemical Studies of Protein-Bound Chromophores, UV-Light Induced DNA Damages, and Lignin Formation

    Author : Bo Durbeej; Leif Eriksson; Tim Clark; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Quantum chemistry; quantum chemistry; calculations; density functional theory; excited states; photochemistry; chromophores; absorption spectra; bathochromic shift; isomerization; UV radiation; DNA damages; cycloaddition reactions; photoenzymic repair; electron transfer; lignin; polymerization; phenoxy radicals; dilignols; Kvantkemi; Quantum chemistry; Kvantkemi;

    Abstract : Quantum chemical methods have been used to provide a better understanding of the photochemistry of astaxanthin and phytochromobilin; the photoenzymic repair of UV-light induced DNA damages; and the formation of lignin. The carotenoid astaxanthin (AXT) is responsible for the colouration of lobster shell. READ MORE

  7. 25. Structure and spectroscopy of bio- and nano-materials from first-principles simulations

    Author : Weijie Hua; Yi LUO; Mauro Stener; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; soft x-ray spectroscopy; bio- and nano-materials; first-principles simulation; host-guest interaction; generalized energy-based fragmentation; Quantum chemistry; Kvantkemi; Spectroscopy; Spektroskopi; SRA - Molecular Bioscience; SRA - Molekylär biovetenskap;

    Abstract : This thesis is devoted to first-principles simulations of bio- and nano-materials,focusing on various soft x-ray spectra, ground-state energies and structures of isolated largemolecules, bulk materials, and small molecules in ambient solutions. K-edge near-edge x-ray absorption fine structure (NEXAFS) spectra, x-ray emission spectra, andresonant inelastic x-ray scattering spectra of DNA duplexes have been studied by means oftheoretical calculations at the density functional theory level. READ MORE