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Showing 1 to 20 of 42 for “"Kohn-Sham"”.
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From Hartree Product to Kohn-Sham and Beyond: Exploring Self-Interaction in Self-Consistent Field Methods
… (SIE) is a commonly known problem that most Kohn-Sham density functional theory (KS-DFT) approximate functionals display to varying extents. It originates from the incomplete cancellation of the Coulomb self-repulsion by the approximate exchange functionals. This is one of the major …
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Ab Initio Treatment of Complex Systems Kohn-Sham Orbitals for Multi Reference Methods and the Base Pairing Properties of Xanthine
Die vorliegende Arbeit besteht aus zwei Teilen. Der erste untersucht die Eignung von LHF-Orbitalen für Multireferenzverfahren. Das Ziel dieses Teils ist eine effizientere Berechnung angeregter Zustände, was zur spektroskopischen Charakterisierung vieler organischer und bioorganischer Moleküle …
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Taming the Inverse and Forward Problems in Density Functional Theory
… the ground-state density $n(x)$ that minimises a Kohn-Sham total energy functional defined using some exchange-correlation (xc) functional $E_\text{xc}[n]$. Towards this end, the associated Euler-Lagrange equations, i.e. the Kohn-Sham equations, are often solved in practice, which demand a …
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A Dirac all-electron basis and spin-orbit coupled projector implementation of the Projector Augmented Wave Method for atomic systems
… the exact eigenfunctions and eigenvalues of the Kohn-Sham equations for large-scale ab-initio electronic structure calculations of molecules and solids, for which exact calculations are impractical. Relativistic and spin-orbit effects are significant for valence electrons of magnetic and …
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Electronic States near Surfaces - a) Analysis of calculation methods using semi-infinite boundary conditions; b) Sensitive detection using laser photoelectron spectroscopy
… The "SI-PAW" method is designed to solve the Kohn-Sham equations within the projector augmented wave "PAW" formalism with boundary conditions appropriate for the semi-infinite geometry of material surfaces. This method, which directly distinguishes between bulk, surface, and defect states, is …
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Development of more accurate computational methods within linear-scaling density functional theory
Kohn-Sham Density Functional Theory (DFT) provides a method for electronic structure calculations applicable to a wide variety of systems. Traditional implementations of DFT are cubic-scaling which limits the size of the systems that can be studied. However recently developed linear-scaling …
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Theory of density functionals
… for its simplicity and rigor is the theory of Kohn and Sham. In this thesis I propose new methods in density-functional theory that are helpful to address some important problems in the application of the local-density approximation within Kohn-Sham DFT to the analysis of ground-states and …
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Theoretical and Computational Aspects of the Optimized Effective Potential Approach within Density Functional Theory
… explicitly upon occupied and unoccupied Kohn–Sham orbitals are considered necessary to address these and other issues. This dissertation considers certain issues relevant to the successful implementation of explicitly orbital-dependent functionals through the optimized effective potential …
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Construction of first-principles density functional approximations and their applications to materials
Kohn-Sham density functional theory is a rigorous formulation of many-electron quantum mechanics which, for practical purposes, requires approximation of one term in its total energy expression: the exchange-correlation energy. This work elucidates systematic methods for constructing approximations …
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Linear scaling density functional theory with Gaussian orbitals and periodic boundary conditions
… methodological and computational details of our Kohn-Sham density functional method with Gaussian orbitals for systems with periodic boundary conditions (PBC). When solving iterative self-consistent field (SCF) equations of density functional theory (DFT), the most computationally demanding tasks …
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On the prediction of electronic stopping power from first principles
… wavefunctions according to the time-dependent Kohn-Sham equation. The wavefunctions are numerically integrated according to the Crank-Nicolson integrator algorithm. In this work a correction to the existing Crank-Nicolson algorithm was implemented in parallel, based on using the correct …
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Development, validation, and application of new relativistic methods for all-electron unrestricted two-component calculations of EPR parameters
… g-tensor within the Resolution of Identity Dirac Kohn Sham method developed by Stanoslav Komorovsky and Michal Repisky in collaboration with other members of the group of V. G. Malkin. All these approaches have been extensively validated.
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Describing Charge Transfer in Extended Donor-Acceptor Systems with Density Functional Theory
… density functional within the generalized Kohn-Sham (GKS) scheme of DFT. Its main ingredient is the range-separation parameter that determines the splitting between long- and short-range exchange. It is obtained from first principles by enforcing the ionization potential theorem of GKS …
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Computer Modeling of Silicon Quantum Dot Floating -Gate Flash Memory Devices
… solution of three-dimensional (3-D) Poisson and Kohn-Sham equations within the density functional formalism, where the quantum many-body interactions are treated according to the local-density approximation. We investigate the quantum-dot electronic structure, device capacitance-voltage …
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Hybrid density functionals with proper exact exchange
… potential of the generalized Kohn–Sham DFT.
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Excited states and electron transfer in solution : models based on density functional theory
… of [Delta]SCF known as restricted open-shell Kohn-Sham (ROKS) theory. We resolve a known ambiguity in the formal solution of the ROKS equations for the singlet excited state by presenting a self-consistent implementation of ROKS with respect to the mixing angle between the two open shells. The …
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Correlated electron dynamics and memory in time-dependent density functional theory
… vieler wechselwirkender Elektronen auf das Kohn-Sham-System nicht-wechselwirkender Teilchen abgebildet wird, das die exakte Elektronendichte reproduziert. Da dieses Hilfssystem auf Einteilchengleichungen beruht, können numerische Berechnungen wesentlich effizienter durchgeführt werden als …
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Electronic, thermoelectric and optical properties of vanadium oxides: VO2, V2O3 and V2O5
… In this study, we have performed one electron Kohn-Sham electronic band-structure calculations of VO_3, V_3O_3 and V_2O_5 in both metallic and insulating phases, implementing a full ab-initio simulation package based on Density Functional Theory (DFT), Plane Waves and Pseudopotentials (PPs). …
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Charge and excitation-energy transfer in time-dependent density functional theory
… of the self-interaction correction in Kohn-Sham DFT that is based on the generalized optimized effective potential to TDDFT using a real-time propagation approach. The multiplicative Kohn-Sham potential allows for a transparent analysis of the exchange-correlation potential during …
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Ab-initio molecular dynamics studies of laser- and collision-induced processes in multielectron diatomics, organic molecules and fullerenes
… physical process, well suited basis sets for the Kohn-Sham orbitals has to be chosen. For the ionization process a novel absorber acting in the energy space as well as additional basis functions will be used depending on the laser frequency. In the first part of the applications, a large variety …
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