Sökning: "Configuration-interaction"

Visar resultat 1 - 5 av 11 uppsatser innehållade ordet Configuration-interaction.

1. 1. Atomic Structure Calculations Using Configuration-Interaction And Many-Body Perturbation Theory For Spectral Modelling Of Neutron Star Mergers : Example Of Ce I - Iv

   L3-uppsats, Uppsala universitet/Teoretisk fysik

   Författare :Fredrik Plane; [2023]
   Nyckelord :Computational atomic physics; Atomic physics; Physics; Astronomy; Astrophysics; Neutron stars; Stars; Relativisitc atomic physics; Configuration-interaction; Perturbation theory; Many-body perturbation theory;

   Sammanfattning : The binary neutron star merger of 2017 and its corresponding electromagnetic signature resembling that of a kilonova has been one of the most groundbreaking astrophysical occurrences in the last decade. Indications of r-process nucleosynthesis in this event presents new opportunities for learning about the astrophysical origin of heavy elements. LÄS MER

3. 2. Beyond the Gross-Pitaevskii Equation: A Perturbative Approach

   Master-uppsats, Lunds universitet/Fysiska institutionen; Lunds universitet/Teknisk fysik (CI)

   Författare :Anton Johansson; [2023]
   Nyckelord :Gross-Pitaevskii; Beyond mean-field; Many-body Perturbation Theory; Bose-Einstein Condensate; BEC; Physics and Astronomy;

   Sammanfattning : We propose and implement a beyond Gross-Pitaevskii approach based on Many-Body Perturbation theory (MBPT) for the study of Bose-Einstein Condensate (BECs) ground states. Two partitions of the system Hamiltonian are considered. LÄS MER

4. 3. Full Configuration Interaction Model for 1-D Quantum System

   Kandidat-uppsats, Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

   Författare :Adam Asaad; [2022]
   Nyckelord :Physics and Astronomy;

   Sammanfattning : The many-body problem is one of the most challenging problems in physics due to the complexity emerging from the interactions of many quantum particles. Since the advent of computers with increasing power, computational methods have been very successful in providing insight and precise solutions to this problem. LÄS MER

5. 4. Beyond Mean-Field Description of Bose-Einstein Condensate

   Kandidat-uppsats, Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

   Författare :Daniel Larsson Persson; [2021]
   Nyckelord :Bose-Einstein condensate; BEC; dilute; non-uniform; quantum depletion; second quantisation; mean field; mean-field approximation; the Gross-Pitaevskii equation; Gross-Pitaevskii; perturbation theory; many-body perturbation theory; Rayleigh-Schrödinger perturbation theory; Rayleigh-Schrödinger; Epstein-Nesbet perturbation theory; Epstein-Nesbet; quantum ring; Physics and Astronomy;

   Sammanfattning : This thesis work is on the theoretical description of dilute Bose-Einstein condensates (BEC) that are non-uniform, meaning that more than one single-particle state is occupied. This phenomenon is usually called quantum depletion. LÄS MER

7. 5. Microscopic and Macroscopic Samples of Atoms in Superposition States Studied by Attosecond Pulses

   Magister-uppsats, Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

   Författare :Axel Stenquist; [2021]
   Nyckelord :Mathematical physics; Theoretical physics; Atomic physics; Attosecond physics; Ultra-fast physics; Numerical simulations; Microscopic; Mesoscopic; Macroscopic; Superposition; Light matter interaction; Quantum mechanics; Electromagnetism; Semiclassical; Attosecond transient absorption spectroscopy; ATAS; Förster resonance; FRET; Two-atom model; Inter-atomic interaction; Dipole-dipole interaction; Many-atom model; Collective coherent effects; Time-dependent configuration-interaction singles; TDCIS; Physics and Astronomy;

   Sammanfattning : In the present thesis, the interaction between atoms in superposition states and attosecond pulses is studied from the microscopic to the macroscopic regime. Using a semi-classical framework, three different models have been explored in order to investigate attosecond light--matter interaction processes. LÄS MER