Search for dissertations about: "A. Kohn"

Showing result 21 - 25 of 30 swedish dissertations containing the words A. Kohn.

  2. 21. Sparse Matrices in Self-Consistent Field Methods

    Author : Emanuel Rubensson; Pawel Salek; Hans Ågren; Anders Niklasson; Axel Ruhe; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; sparse matrix; self-consistent field; Hartree-Fock; Density Functional Theory; Density Matrix Purification; Theoretical chemistry; Teoretisk kemi;

    Abstract : This thesis is part of an effort to enable large-scale Hartree-Fock/Kohn-Sham (HF/KS) calculations. The objective is to model molecules and materials containing thousands of atoms at the quantum mechanical level. HF/KS calculations are usually performed with the Self-Consistent Field (SCF) method. READ MORE

  4. 22. Density Functionals for Dynamic Linear Response in Finite Systems

    Author : Maria Hellgren; Matematisk fysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES;

    Abstract : This dissertation investigates a new method for obtaining excited-state properties of finite, many-electron systems such as atoms, molecules and nano-systems. The method combines the merits of many-body perturbation theory and time-dependent perturbation theory and yields approximate density response functions which preserve basic physical conservation laws. READ MORE

  5. 23. Density functional studies of EPR and NMR parameters of paramagnetic systems

    Author : Lyudmyla G. Telyatnyk; Olav Vahtras; Martin Kaupp; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; spin-restricted DFT; restricted-unrestricted approach; EPR spin Hamiltonian parameters; NMR spin Hamiltonian parameters; Bioorganic chemistry; Bioorganisk kemi;

    Abstract : Experimental methods based on the magnetic resonance phenomenon belong to the most widely used experimental techniques for investigations of molecular and electronic structure. The difficulty with such experiments, usually a proper interpretation of data obtained from high-resolution spectra, opens new challenges for pure theoretical methods. READ MORE

  6. 24. Memory Effects on Iron Oxide Filled Carbon Nanotubes

    Author : Carlos Cava; Clas Persson; Lucimara Roman; Krister Svensson; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Memory devices; Carbon Nanotubes; energy; nanotechnology; Iron Oxide;

    Abstract : In this Licentiate Thesis, the properties and effects of iron and iron oxide filled carbon nanotube (Fe-CNT) memories are investigated using experimental characterization and quantum physical theoretical models. Memory devices based on the simple assembly of Fe-CNTs between two metallic contacts are presented as a possible application involving the resistive switching phenomena of this material. READ MORE

  7. 25. Efficient Density Matrix Methods for Large Scale Electronic Structure Calculations

    Author : Anastasia Kruchinina; Emanuel H. Rubensson; Elias Rudberg; David Bowler; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; electronic structure; linear scaling; density matrix; density functional theory; Hartree-Fock; recursive polynomial expansion; density matrix purification; eigenvectors; molecular orbitals; stopping criteria; inverse factorization; matrix sparsity; parallelization; Scientific Computing; Beräkningsvetenskap;

    Abstract : Efficient and accurate methods for computing the density matrix are necessary to be able to perform large scale electronic structure calculations. For sufficiently sparse matrices, the computational cost of recursive polynomial expansions to construct the density matrix scales linearly with increasing system size. READ MORE