This thesis is divided into three chapters. In the first chapter we outline a simple and numerically inexpensive approach to describe the spectral features of the single-impurity Anderson model. The method combines aspects of the density matrix embedding theory (DMET) approach with a spectral broadening approach inspired by those used in numerical renormalization group (NRG) methods. At zero temperature for a wide range of U , the spectral function produced by this approach is found to be in good agreement with general expectations as well as more advanced and complex numerical methods such as DMRG-based schemes. The theory developed here is simply transferable to more complex impurity problems The second chapter outlines the density matrix embedding methodology in the context of electronic structure applications. We formulate analytical gradients for energies obtained from DMET focusing on two scenarios: RHF-in-RHF embedding and FCI-in-RHF embedding. The former involves solving the small embedded system at Restricted Hartree-Fock (RHF) level of theory. This serves to check the validity of the formulas by reproducing the RHF results on the full system for energies and gradients. The latter scenario employs full configuration interaction (FCI) as a high level solver for the small embedded system. Our results show that only Hellmann-Feynman terms, which involve derivatives of one- and two-electron terms in the atomic orbital basis, are required to calculate energy gradients in both cases. We applied our methodology to the problem of H 10 ring dissociation where the analytical gradients matched those obtained numerically. The gradient formulation is applicable to geometry optimization of strongly correlated molecules and solids. It can also be used in ab initio molecular dynamics where forces on nuclei are obtained from DMET energy gradients. In the final chapter we focus on the study of finite-temperature equilibrium properties of quantum systems in continuous space. We formulate an expansion of the partition function in continuous-time and use Monte Carlo to sample terms in the resulting infinite series. Such a strategy has been highly successful in quantum lattice models but has found scant application in off-lattice systems. The Monte Carlo estimate of the average energy of quantum particles in continuous space subject to simple model potentials is found to converge with low statistical error to the exact solutions even when very high perturbation order is required. We outline two ways in which the algorithm can be applied to more complex problems. First, by drawing an analogy between the formulation in continuous-time with the discretized, Trotter factorized version of standard path integral Monte Carlo (PIMC). This allows one to use the suite of standard PIMC moves to carry out the position sampling required to obtain the weight of each time configuration. Finally, we propose an alternate route by fitting the many-particle potential with multidimensional Gaussians which provides an analytical form for the position integrals.

Orientador: George Gershon Kleiman / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica "Gleb Wataghin" / Made available in DSpace on 2018-09-24T18:16:54Z (GMT). No. of bitstreams: 1 Pepino_RafaelTristao_D.pdf: 1812944 bytes, checksum: 550eec7ef23027d3eca186c3ea0929a7 (MD5) Previous issue date: 2002 / Resumo: Investigamos a transferência de carga no problema do acoplamento dependente do tempo entre um estado localizado e um continuum. Utilizamos uma generalização do Hamiltoniano de Newns-Anderson, que possibilita a abordagem simultânea de processos quasi-ressonantes e Auger. Obtivemos soluções exatas admitindo transições Auger muito rápidas comparadas à duração do acoplamento Auger, e um modelo de banda lorentziana, com largura e centro em G e centro ec, para os processos quasi-ressonantes. Investigando a ocupação no estado localizado ao longo do tempo e o espectro de estados ativos do continuum, elucidamos os papéis físicos de G , de ec, do potencial de interação quasi-ressonante V , do tempo médio de duração desta interação t, da posição do nível de Fermi eF, do deslocamento do estado localizado ea(t) e da intensidade de acoplamento Auger L0. Aplicamos com sucesso a teoria ao entendimento dos experimentos de neutralização de gases nobres espalhados por superfícies sólidas / Abstract: We investigate charge exchange processes considering the time dependent coupling between a localized state and a continuum. We use a generalized Newns-Anderson Hamiltonian, that allows an approach which treats quasi-resonant and Auger processes on an equal footing. We obtain exact solutions assuming that the Auger transitions were very fast compared to the Auger coupling duration, and that the band involved in quasi-resonant processes was lorentzian shaped, with half width G and centre at ec. Investigating the localized state occupation and the spectrum of continuum active states as functions of time, we elucidate the roles played by G by ec, by the quasi-resonant interaction potential V, by the mean time of this interaction t, by the Fermi level eF, by the localized state energy ea(t) and by the Auger coupling strength L0. We successfully apply the theory to explain experiments of neutralization of noble gases scattered from solid surfaces / Doutorado / Física / Doutor em Ciências

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Writer, producer and director Wes Anderson’s unusual and idiosyncratic films take place in world which seems to be entirely his own. Often anachronistic and highly stylized, the Andersonian universe looks like little else being shown in contemporary cinemas. Yet, Anderson is also one of the most allusive filmmakers working today. Littered throughout his oeuvre are endless allusions to films, directors, authors and books which have had significant influence on Anderson as an artist. In fact, Anderson’s films can only be fully appreciated when viewed through the lens of his many sources, since his films emerge as he carefully collects, compiles and crafts his many influences into a sort of collage. In order to understand how this dichotomy operates in Anderson’s work I examine the influence of several key directors, authors, and films. Through this study I show that one of the things that make Anderson unique is the very way in which he interacts with the sources to which he is alluding. It is his uncommon ability to weave homage and critique together which makes him a truly allusive auteur.

There is no abstract available for this thesis.

Writer, producer and director Wes Anderson’s unusual and idiosyncratic films take place in world which seems to be entirely his own. Often anachronistic and highly stylized, the Andersonian universe looks like little else being shown in contemporary cinemas. Yet, Anderson is also one of the most allusive filmmakers working today. Littered throughout his oeuvre are endless allusions to films, directors, authors and books which have had significant influence on Anderson as an artist. In fact, Anderson’s films can only be fully appreciated when viewed through the lens of his many sources, since his films emerge as he carefully collects, compiles and crafts his many influences into a sort of collage. In order to understand how this dichotomy operates in Anderson’s work I examine the influence of several key directors, authors, and films. Through this study I show that one of the things that make Anderson unique is the very way in which he interacts with the sources to which he is alluding. It is his uncommon ability to weave homage and critique together which makes him a truly allusive auteur.

Thesis (D. Min.)--Nazarene Theological Seminary, 1989. / Includes bibliographical references (leaves 141-143).

Thesis (M.S. - Renewable Natural Resources)--University of Arizona, 1982. / Includes bibliographical references (leaves 72-78).

Thesis (Ph. D.)--University of North Texas, Dec., 2007. / Title from title page display. Includes bibliographical references.