Search for dissertations about: "dft formalism"

Showing result 1 - 5 of 15 swedish dissertations containing the words dft formalism.

  1. 1. Nonlocal Correlations in Density Functional Theory

    Author : Henrik Rydberg; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; bonding; GGA; adhesion; graphene; DFT; exchange; adsorption; LDA; first principles; polarization; vdW; determinants; correlation; graphite; surface states; van der Waals; density-functional theory; physisorption; nonlocal; functional;

    Abstract : In Density Functional Theory, the widely used local and semilocal approximations to the exchange-correlation energy, the local density approximation (LDA) and the generalized gradient approximations (GGAs), lack a physical description of truly nonlocal correlation effects, which are absolutely essential for a proper description of soft matter. A scheme is proposed that provides a basis for systematic improvements beyond LDA and GGA, including correlations at intermediate and long range, giving rise to bonds of pure van der Waals type as well as more intricate, intermediate-range correlation bonds. READ MORE

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

    Author : Miroslav Hopjan; Matematisk fysik; []
    Keywords : 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;

    Abstract : 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. READ MORE

  3. 3. First-principles Studies of Local Structure Effects in Magnetic Materials

    Author : Marcio Costa; Anders Bergman; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; magnetic anisotropy; DMFT; magnetism; DFT; Materialvetenskap; Materials Science;

    Abstract : This thesis focus on the magnetic behavior, from single atoms to bulk materials. The materials considered in this thesis have been studied by computational methods based on ab initio theory, density functional theory (DFT), including treatment of the spin-orbit coupling, non-collinear magnetism, and methods capable of treating discorded systems. READ MORE

  4. 4. Theoretical studies of EPR parameters of spin-labels incomplex environments

    Author : Bogdan Frecus; Hans Ågren; Chiara Cappelli; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; EPR; DFT; spin-labels; QM MM; Breit-Pauli Hamiltonian;

    Abstract : This thesis encloses quantum chemical calculations performed in the framework of density functional response theory for evaluating electron paramagnetic resonance (EPR) spin Hamiltonian parameters of various spin-labels in different environments. These parameters are the well known electronic g-tensor and the nitrogen hyperfine coupling constants, which are extensively explored in this work for various systems. READ MORE

  5. 5. Ionic and electronic transport in electrochemical and polymer based systems

    Author : Anton Volkov; Igor Zozoulenko; Magnus Berggren; Xavier Crispin; Yury Gogotsi; Linköpings universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Modeling; Charge transport; Charge carriers Electrochemical systems; Polymer; PEDOT:PSS; Supercapacitance; Cyclic voltammetry; double layers; Nernst-Planck-Poisson; DFT; TDDFT; Ion Bipolar Junction Transistor; ETE-S;

    Abstract : Electrochemical systems, which rely on coupled phenomena of the chemical change and electricity, have been utilized for development an interface between biological systems and conventional electronics.  The development and detailed understanding of the operation mechanism of such interfaces have a great importance to many fields within life science and conventional electronics. READ MORE