Sökning: "time-dependent density functional theory"

Visar resultat 16 - 20 av 41 avhandlingar innehållade orden time-dependent density functional theory.

  1. 16. Theoretical perspectives on ultrafast and non-linear spectroscopy

    Författare :Emil Vinas Boström; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Non-linear optics; Ultrafast dynamics; Non-equilibrium Green s functions; Density functional theory; Multi-photon absorption; Second harmonic generation; Desorption dynamics; Auger decay; Charge-separation dynamics; Quantum Zeno effect; Fysicumarkivet A:2018:Vinas Boström;

    Sammanfattning : In this thesis we discuss a theoretical description of ultrafast and non-linear spectroscopy. Due to the high intensities and ultrashort pulse durations involved in such experiments, it is necessary to use an explicitly time-dependent formalism. LÄS MER

  3. 17. X-ray spectroscopies through damped linear response theory

    Författare :Thomas Fransson; Patrick Norman; Christoph Jacob; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : In order to reach a fundamental understanding of interactions between electromagnetic radiation and molecular materials, experimental measurements need to be supplemented with theoretical models and simulations. With the use of this combination, it is possible to characterize materials in terms of, e.g. LÄS MER

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

    Författare :Maria Hellgren; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : 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. LÄS MER

  5. 19. Ground and Excited State Aromaticity : Design Tools for π-Conjugated Functional Molecules and Materials

    Författare :Christian Dahlstrand; Henrik Ottosson; Miguel Solà; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; fulvene; fulvalene; polyfulvene; aromaticity; triplet state; excited state; Clar structure; polybenzenoid hydrocarbons PBH ; conjugated polymers; computational chemistry; optical spectroscopy; Kemi med inriktning mot organisk kemi; Chemistry with specialization in Organic Chemistry;

    Sammanfattning : The main focus of this thesis is on the aromaticity of the ground state and electronically excited states of π-conjugated molecules and polymers, as well as how aromaticity is connected to their properties.The electronic structures of polybenzenoid hydrocarbons (PBHs) were explored through density functional theory (DFT) calculations and the π-component of the electron localization function (ELFπ). LÄS MER

  7. 20. Theoretical Developments for the Real-Time Description and Control of Nanoscale Systems

    Författare :Miroslav Hopjan; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Green’s Function; DFT; TDDFT; Hubbard Model; Many-Body Perturbation Theory; Strongly Correlated Systems; Quantum Transport; Disorder; Ehrenfest Dynamics; Electronic Friction; Exact Diagonalization; Periodic Anderson Model; Fysicumarkivet A:2018:Hopjan;

    Sammanfattning : In this thesis we focus on improvements of the description of the electron-electron correlation effects in nonequilibrium nanosystems. We mainly focus on developments of two nonequilibrium methods, namely the formalism of Nonequilibrium Green’s Function and Time Dependent Density Functional Theory and we explore the possibility to improve existing approximations in these theories. LÄS MER