Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 31 for “"ground state properties"”.
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Impurities in a Bose-Einstein condensate using quantum Monte-Carlo methods: ground-state properties.
In this thesis we investigate the properties of impurities immersed in a dilute Bose gas at zero temperature using quantum Monte-Carlo methods. The interactions between bosons are modeled by a hard sphere potential with scattering length a, whereas the interactions between the impurity and the …
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Electronic Structure and Emergent Orders in Correlated Nickelates
… with novel functionalities and exotic physical properties that escapes the conventional description of quantum mechanics. Rare earth nickelate compounds have been established as archetypal correlated quantum materials with rich diversity of ground-state properties that emerge due to the …
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Theoretical study of interacting low dimensional electron systems
… and overlayer-site orbital energy. The ground-state properties are investigated and discussed in a many-body picture.
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Developments in the Theory of X-ray Absorption and Compton Scattering.
… physics for studying electronic and chemical properties of materials. Theoretical approaches for studying x-ray absorption (XAS) and x-ray photoemision (XPS) properties are described by single particle Green’s function theory. In strongly correlated systems, such as transition metal oxides, it …
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Calculations of small transition metal molecules relating to catalysis
… ScH, MnH, NiH, CuH, NiH2, and CuH2. Both ground state properties and potential energy curves were obtained. It was found that the transition metal 3d-orbitals do not participate significantly in the bonding of these molecules. Rather, the bonds involve mainly the 4s and 4sp hybrid …
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Shining a Light on the Nucleus: Photonuclear Measurements from Correlations to Charmonium
… to draw quantitative conclusions regarding the ground-state properties of SRCs. The studies described in this thesis represent the first global analysis of SRC breakup measurements in order to present a unified picture of SRCs within light- to medium-size nuclei. This includes the use of a novel …
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Pionless Effective Field Theory: Building the Bridge Between Lattice Quantum Chromodynamics and Nuclear Physics
We analyze ground state properties of few-nucleons systems and $^{16}$O using \eftnopi (Pionless Effective Field Theory) at \ac{LO}. This is the first time the theory is extended to many-body nuclear systems. The free constants of the interaction are fitted using both experimental data and …
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EXOTIC PHASES IN A SPIN-1 BOSONIC FLUX SYSTEM
… study, using the optimisation of matrix product states, the ground state properties of an interacting spin-1 hardcore boson model on a ladder in a transverse magnetic field at zero temperature. At unit filling in the strong-interacting regime, we observe a Mott insulator phase characterised by a …
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The effects of Landau level mixing, finite thickness, and external electric fields on the $\nu=\frac{5}{2}$ fractional quantum Hall effect
… and interesting experimental and theoretical state. A great deal of experimental, theoretical and numerical work suggests that this state may support quasihole excitations with non-Abelian statistics, where the order of particle exchange influences the final state of the system. Thus, the …
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Structural, vibrational and thermodynamic properties of carbon allotropes from first-principles : diamond, graphite, and nanotubes
The structural, dynamical, and thermodynamic properties of different carbon allotropes are computed using a combination of ab-initio methods: density-functional theory for total-energy calculations and density-functional perturbation theory for lattice dynamics. For diamond, graphite, graphene, and …
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Local Hamiltonians in quantum computation
… with local Hamiltonians and finding their ground state properties. I give a numerical method for finding the ground state of translationally invariant Hamiltonians on an infinite tree. This method is based on imaginary time evolution within the Matrix Product State ansatz, and uses a new …
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Improving the Dispersive Optical Model toward a Dispersive Self-energy Method
… experimental observables associated with ground state properties, such as the charge density, particle number, and the energy per particle. Comparison of these quantities with data suggests additional ways in which the dispersive optical model can be improved. For example, a better …
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A quantum Monte Carlo study of the high-pressure phases of solid hydrogen
… which can afford accurate estimates of the ground state properties of quantum many-body problems. We have applied these Monte Carlo methods to the high pressure phases of solid hydrogen to elucidate those parts of the phase diagram where experimental results are inconclusive or lacking. The …
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Dynamics of finite momentum Bose polarons
… variational approach, we study both ground state properties and quench dynamics of the system after a sudden immersion of the impurity into the BEC. We find evidence of a ground state phase transition when the impurity has a velocity greater than that of the sound velocity (Landau …
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Quantum Monte Carlo studies of dense hydrogen and two-dimensional Bose liquids
… in their various incarnations, calculate ground state or finite temperature properties of many-body quantum systems. We apply the path-integral Monte Carlo method to hydrogen at densities and temperatures in the regime of cooperative thermal and pressure dissociation, relevant to …
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Towards Systematic Improvement of Density Functional Approximations
… theory is a formally exact theory to describe ground state properties due to the existence of the exact functional. In practice, the usefulness of density functional theory relies on the accuracy of density functional approximations. After decades of effort of functional developments, the …
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Tensor network states simulations of exciton-phonon quantum dynamics for applications in artifcial light-harvesting
… I developed a powerful tree tensor network states (TTNS) method that finds an optimally compressed explicit representation of the combined electronic and vibrational quantum state. With TTNS it is possible to simulate exciton-phonon quantum dynamics from small molecules to larger complexes, …
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Monte Carlo studies of ground-state & optical properties of multiexcitonic complexes in semiconductors
… and semiconductor impurities. We calculate the ground-state and optical properties of several multiexciton systems within the spherical effective mass approximation, focusing on the role of interparticle correlations which have not been adequately accounted for in previous calculations. We …
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A quantum Monte Carlo study of the two-dimensional electron gas
… previous Monte Carlo methods to study both ground state and excited states of the two-dimensional electron gas. For ground state properties we have used variational and fixed-node diffusion Monte Carlo methods, the latter of which is a nearly exact method for a system of many fermions. With …
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Condensation and pairing in inhomogeneous cold atomic and electronic systems
… and Bardeen-Cooper-Schrieffer (BCS) pairing states in inhomogeneous systems of cold atoms and of electrons. Features of spatially separated phases are explored, with particular focus on the behavior of the condensed phase and its experimental measures. Three specific systems are addressed …
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