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 21 for “"Quantum Monte Carlo methods"”.
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Backflow and pairing wave function for quantum Monte Carlo methods
Quantum Monte Carlo (QMC) methods are a class of stochastic techniques that can be used to compute the properties of electronic systems accurately from first principles. This thesis is mainly concerned with the development of trial wave functions for QMC. An extension of the backflow transformation …
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Application of quantum Monte Carlo methods to molecular potential energy surfaces
<p>"Various computational methods have been used to generate potential energy surfaces, which can help us simulate and interpret how atoms or molecules behave during a chemical reaction. For accurate work, <i>ab initio</i> wavefunction methods have traditionally been used, which have some …
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Application of quantum Monte Carlo methods to excitonic and electronic systems
… with the application and development of quantum Monte Carlo (QMC) methods. We begin by proposing a technique to maximise the efficiency of the extrapolation of DMC results to zero time step, finding that a relative time step ratio of 1:4 is optimal. We discuss the post-processing of QMC …
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Quantum Monte Carlo Methods for First Principles Simulation of Liquid Water
… are very long, on the order of thousands of Monte Carlo cycles or picoseconds of Molecular Dynamics integration. Thus a great deal of computational effort is required to generate statistically independent, well-converged data. This problem affects all water simulations, but the implications …
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Quantum Monte Carlo methods for molecular systems: New developments and applications
… been to: (i) expand the applicability of the quantum Monte Carlo (QMC) methods to larger molecular systems and check the reliability of traditional approaches, (ii) determine the impact of correlation energy on a variety of systems in which correlation is important, (iii) investigate new …
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Quantum Monte Carlo methods for molecular systems: New developments and applications
… been to: (i) expand the applicability of the quantum Monte Carlo (QMC) methods to larger molecular systems and check the reliability of traditional approaches, (ii) determine the impact of correlation energy on a variety of systems in which correlation is important, (iii) investigate new …
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Projector Quantum Monte Carlo Methods for Linear and Non-linear Wavefunction Ansatzes
… is concerned with the development of a Projector Quantum Monte Carlo method for non-linear wavefunction ansatzes and its application to strongly correlated materials. This new approach is partially inspired by a prior application of the Full Configuration Interaction Quantum Monte Carlo (FCIQMC) …
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Application of quantum Monte Carlo methods to homogeneous electron and electron-hole systems
… the practical solution of the equations of quantum mechanics remains a challenging area of research. This thesis is concerned with the application of quantum Monte Carlo methods to two model systems: the spin-polarised homogeneous electron gas, and a hole-doped electron gas. Electronic …
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Impurities in a Bose-Einstein condensate using quantum Monte-Carlo methods: ground-state properties.
… 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 bosons are modeled by a short-range, square-well potential where both …
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Quantum Monte Carlo Methods applied to strongly correlated and highly inhomogeneous many-Fermion systems
Quantum Monte Carlo Methods applied to strongly correlated and highly inhomogeneous many-Fermion systems
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Study of Ultracold Fermi Gases in the BCS-BEC Crossover: Quantum Monte Carlo Methods, Hydrodynamics and Local Density Approximation.
… and also for addressing fundamental issues of quantum mechanics as well as for simulating more complex physical systems such as those encountered in condensed matter. Even if the effective hamiltonian of ultracold gases can be simple, due to the diluteness of the system and the low temperature, …
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A Quantum Monte Carlo approach to dark matter-nuclei interaction
Using quantum Monte Carlo Methods, we compute the differential cross sections for elastic scattering of dark matter (DM) particles off light nuclei, up to $A=6$ (d, $^3$H, $^3$He, $^4$He, and $^6$Li). DM-nucleon one- and two-body currents are obtained to next-to-leading order in chiral effective …
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Novel Quantum Monte Carlo Approaches for Quantum Liquids
Quantum Monte Carlo methods are a powerful suite of techniques for solving the quantum many-body problem. By using random numbers to stochastically sample quantum properties, QMC methods are capable of studying low-temperature quantum systems well beyond the reach of conventional deterministic …
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Pairing and entanglement: quantum Monte Carlo studies
Described in this dissertation is the use of quantum Monte Carlo methods to study two ideas in quantum many-body problems: superfluidity and entanglement. Density matrices are presented a central tool in the analysis, as are discussed in the review of path integral Monte Carlo (PIMC) and …
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Quantum Monte Carlo study of low dimensional materials
… which have rarely or never been studied using quantum Monte Carlo methods. It begins with an investigation into weak van der Waals-like interactions in bilayer graphene and extends to graphene placed on top of boron nitride at four different stacking configurations. The in-plane optical phonon …
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Fluctuations and Instantons in Complex Landscapes: From Ligand Unbinding to Proton Transfer
… entail ab initio molecular dynamics (AIMD) and quantum Monte Carlo methods (QMC) for computational enzymology. An ideal system for the application of AIMD, are the cytochromes P450 (CYP450s). Most AIMD calculations are performed using plane-wave (PW) density functional theory as an electronic …
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Algorithms for quantum simulation: design, analysis, implementation, and application
Simulating the Hamiltonian dynamics of quantum systems is one of the most promising applications of digital quantum computers. In this dissertation, we develop an understanding of quantum simulation algorithms concerning their design, analysis, implementation, and application. We implement three …
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Zigzag Phase Transition in Quantum Wires and Localization in the Inhomogeneous One-Dimensional Electron Gas
… is described by Luttinger Liquid theory. We use Quantum Monte Carlo methods to study two situations that are beyond Luttinger Liquid theory --- the quantum phase transition from a linear 1D electron system to a quasi-1D zigzag arrangement, and electron localization in quantum point contacts. …
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Study of the properties of dilute Fermi gases in the strongly interacting regime
Quantum degenerate Fermi gases can be created in the laboratories using alkali atoms. These gases can be in different regimes of density and interaction strength and provide an ideal test bed for the basic properties of the quantum and statistical mechanics. Also some astrophysical objects such as …
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Monte Carlo methods: application to hydrogen gas and hard spheres
Quantum Monte Carlo (QMC) methods are among the most accurate for computing ground state properties of quantum systems. The two major types of QMC we use are Variational Monte Carlo (VMC), which evaluates integrals arising from the variational principle, and Diffusion Monte Carlo (DMC), which …
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