Search for dissertations about: "coupled-cluster"

Showing result 1 - 5 of 10 swedish dissertations containing the word coupled-cluster.

2. 1. On the role of the electron-electron interaction in two-dimensional quantum dots and rings

   Author : Erik Waltersson; Eva Lindroth; Stephanie Reimann; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; quantum dot; quantum ring; quantum dot molecule; electronic structure; two-dimensional; many-body physics; many-body perturbation theory; coupled cluster; coupled cluster singles and doubles; quantum logical gates; quantum computing; quantum control; quantum control algorithm; Electronic structure; Elektronstruktur; fysik; Physics;

   Abstract : Many-Body Perturbation Theory is put to test as a method for reliable calculations of the electron-electron interaction in two-dimensional quantum dots. We show that second order correlation gives qualitative agreement with experiments on a level which was not found within the Hartree-Fock description. READ MORE

4. 2. Many-Body effects in Semiconductor Nanostructures

   Author : Carl-Johan Wesslén; Eva Lindroth; Morten Førre; Stockholms universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; coupled cluster; nanostructure; quantum dot; quantum ring; concentric quantum ring; many body pertubation theory; fysik; Physics;

   Abstract : Low dimensional semiconductor structures are modeled using techniques from the field of many-body atomic physics. B-splines are used to create a one-particle basis, used to solve the more complex many-body problems. READ MORE

5. 3. X-ray absorption spectroscopy through damped coupled cluster response theory

   Author : Thomas Fransson; Patrick Norman; Lars Pettersson; Linköpings universitet; []
   Keywords : ;

   Abstract : For a fundamental understanding of the interaction of electromagnetic radiation and molecular materials, experimental measurements are to be combined with theoretical models. With this combination, materials can be characterized in terms of composition, structure, time-resolved chemical reactions, and other properties. READ MORE

6. 4. Quantum Chemical Studies of Radical Cation Rearrangement, Radical Carbonylation, and Homolytic Substitution Reactions

   Author : Daniel Norberg; Nessima Salhi-Benachenhou; Sten Lunell; Tim Clark; Uppsala universitet; []
   Keywords : Quantum chemistry; quantum chemistry; coupled-cluster; density functional theory; meta-GGA; reaction mechanism; potential energy surface; isomerization; fragmentation; dissociation; condensation; addition; SH2; hydrogen abstraction; iodine atom transfer; complex; weakly interacting system; hyperfine coupling constant; Kvantkemi;

   Abstract : Quantum chemical calculations have been performed to investigate radical cation rearrangement, radical carbonylation, and homolytic substitution reactions of organic molecules. The rearrangement of the bicyclopropylidiene radical cation to the tetramethyleneethane radical cation is predicted to proceed with stepwise disrotatory opening of the two rings. READ MORE

7. 5. Autoionizing states and their relevance in electron-ion recombination

   Author : Dragan Nikolić; Eva Lindroth; Gleb Gribakin; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Electron-ion recombination; Autoionization; Electron correlation calculations; Doubly excited states; Relativistic many-body perturbation theory; Coupled-cluster methodology; Intruder state problem; Physics; Fysik;

   Abstract : Atomic physics plays an important role in determining the evolution stages in a wide range of laboratory and cosmic plasmas. Therefore, the main contribution to our ability to model, infer and control plasma sources is the knowledge of underlying atomic processes. READ MORE