Sökning: "self-consistent field"

Visar resultat 1 - 5 av 61 avhandlingar innehållade orden self-consistent field.

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

3. 2. Topological band theory and Majorana fermions : With focus on self-consistent lattice models

   Författare :Kristofer Björnson; Annica M. Black-Schaffer; Jonas Fransson; Olle Eriksson; Andrei Bernevig; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Topology; Majorana; superconductivity; material physics; numerical calculations; tight-binding; mean-field;

   Sammanfattning : One of the most central concepts in condensed matter physics is the electronic band structure. Although band theory was established more than 80 years ago, recent developments have led to new insights that are formulated in the framework of topological band theory. LÄS MER

4. 3. The spin degeneracy problem in self-consistent field methods

   Författare :Sten Lunell; Uppsala universitet; []
   Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

   Sammanfattning : .... LÄS MER

5. 4. Quantum and quantum-classical calculations of core-ionized molecules in varied environments

   Författare :Tuomas Löytynoja; Hans Ågren; Jukka Tulkki; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Electron spectroscopy; UPS; XPS; photodissociation; binding energy; ionization potential; computational; electronic structure; self-consistent field; DFT; QM MM; gas phase; liquid; solution; physisorption; metallic surface; polymer; charge transfer; Teoretisk kemi och biologi; Theoretical Chemistry and Biology;

   Sammanfattning : Computational quantum chemistry methods have been applied in two particular cases: to provide insight to photoionization induced fragmentation of HgBr2 and HgCl2 molecules, and to study core-electron binding energies and chemical shifts of molecules in liquid, surface adsorbed and polymeric environments in the framework of quantum mechanics/molecular mechanics (QM/MM). In the photodissociation studies the computational work is based on the relativistic Dirac equation as the systems present strong spin-orbit interaction affecting the fragmentation processes. LÄS MER

7. 5. Fingerprints of light-induced molecular transients : from quantum chemical models of ultrafast x-ray spectroscopy

   Författare :Jesper Norell; Michael Odelius; Sang-Kil Son; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; time-resolved x-ray spectroscopy; quantum chemistry; electronic structure; multi-configurational self-consistent field; density functional theory; molecular dynamics; Born-Oppenheimer dynamics; non-adiabatic dynamics; proton-transfer; charge-transfer; solvatization; Dyson orbital; teoretisk fysik; Theoretical Physics;

   Sammanfattning : Absorption of sunlight generates renewable electricity and powers the growth of plants, but also causes severe damage both to synthetic materials and biological tissue. The wildly varying outcomes of these light-induced processes are ultimately determined by much slighter differences in their underlying reaction pathways, induced by the transient properties of short-lived and miniscule molecules; a powerful approach to their detection and characterization is offered by ultrafast x-ray spectroscopy, with identification of spectral fingerprints and further guidance from quantum chemical models. LÄS MER