Accurate Treatments of Electronic Correlation: Phase Transitions in an Idealized One-Dimensional Ferroelectric and Modelling Experimental Quantum Dots

131 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.The second system we have studied is a set of idealized (harmonic) and realistic quantum dots. Two idealized dots, spherical and squashed, quasi-2D structures, are analyzed. In the first QMC is contrasted with a large set of commonly used electronic structure methods including MSFT, KLI, LSDA, and CCSD, and in the second we scrutinize whether SDW states truly exist as predicted by LSDA. In conjunction with the Computational Electronics Group at the Beckman Institute, we have performed QMC calculations on realistically modelled quantum dots in the effective mass approximation. The potentials of these dots are determined using the FEM method to solve Poisson's equation and the effective mass is allowed to spatially vary in our QMC simulations. We find that in arrays of QD's, LSDA may be insufficiently accurate to determine the proper spin states of the electrons. Additionally, we illustrate that QMC has a bright future ahead of it in modelling such devices using arbitrary functions represented on grids using splines.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD