Search for dissertations about: "coupled cluster"

Showing result 1 - 5 of 41 swedish dissertations containing the words coupled cluster.

  1. 1. Magnetic Reconnection in Space Plasmas : Cluster Spacecraft Observations

    Author : Alessandro Retinò; Mats André; Andris Vaivads; Bengt U. Ö. Sonnerup; Uppsala universitet; []
    Keywords : Space and plasma physics; space physics; plasma astrophysics; plasma physics; transport processes; boundary layers; magnetic reconnection; turbulence; particle acceleration; solar system; magnetospheres; Rymd- och plasmafysik;

    Abstract : Magnetic reconnection is a universal process occurring at boundaries between magnetized plasmas, where changes in the topology of the magnetic field lead to the transport of charged particles across the boundaries and to the conversion of electromagnetic energy into kinetic and thermal energy of the particles. Reconnection occurs in laboratory plasmas, in solar system plasmas and it is considered to play a key role in many other space environments such as magnetized stars and accretion disks around stars and planets under formation. READ MORE

  2. 2. 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 : NATURAL SCIENCES; NATURVETENSKAP; 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

  3. 3. Many-Body effects in Semiconductor Nanostructures

    Author : Carl-Johan Wesslén; Eva Lindroth; Morten Førre; Stockholms universitet; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; NATURAL SCIENCES; NATURVETENSKAP; 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

  4. 4. 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

  5. 5. 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