Sökning: "sparse matrices"

Visar resultat 1 - 5 av 30 avhandlingar innehållade orden sparse matrices.

  1. 1. Sparse Matrices in Self-Consistent Field Methods

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

    Sammanfattning : 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. LÄS MER

  2. 2. Sparse Array Architectures for Wireless Communication and Radar Applications

    Författare :Navid Amani; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; base station antenna BSA ; sparse array; grating lobe; multi-user MU MIMO; multipath channel; mutual coupling; direction-of-arrival DOA estimation; MIMO radar; 5G; network theory;

    Sammanfattning : This thesis focuses on sparse array architectures for the next generation of wireless communication, known as fifth-generation (5G), and automotive radar direction-of-arrival (DOA) estimation. For both applications, array spatial resolution plays a critical role to better distinguish multiple users/sources. LÄS MER

  3. 3. Quantum Chemistry for Large Systems

    Författare :Elias Rudberg; Pawel Salek; Christian Ochsenfeld; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quantum chemistry; fast multipole method; density matrix purification; sparse matrices; Theoretical chemistry; Teoretisk kemi;

    Sammanfattning : This thesis deals with quantum chemistry methods for large systems. In particular, the thesis focuses on the efficient construction of the Coulomb and exchange matrices which are important parts of the Fock matrix in Hartree-Fock calculations. LÄS MER

  4. 4. Parallelization of dynamic algorithms for electronic structure calculations

    Författare :Anton G. Artemov; Emanuel H. Rubensson; Maya Neytcheva; Bo Kågström; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; parallelization; task-based programming; matrix algorithms; sparse matrices; inverse factorization; localized computations; density matrix methods; electronic structure calculations; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : The aim of electronic structure calculations is to simulate behavior of complex materials by resolving interactions between electrons and nuclei in atoms at the level of quantum mechanics. Progress in the field allows to reduce the computational complexity of the solution methods to linear so that the computational time scales proportionally to the size of the physical system. LÄS MER

  5. 5. Preconditioning for block matrices with square blocks

    Författare :Ivo Dravins; Maya Neytcheva; Svetozar Margenov; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; preconditioning; block preconditioning; PDE-constrained optimization; Implicit Runge-Kutta methods; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Sammanfattning : Linear systems of equations appear in one way or another in almost every scientific and engineering problem. They are so ubiquitous that, in addition to solving linear problems, also non-linear problems are typically reduced to a sequence of linear ones. LÄS MER