The Study of Strongly Correlated Electronic Systems using Dynamical Mean field Theory
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Date
2016-06
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Addis Ababa University
Abstract
The physics of strongly correlated electronic systems has attracted much attention
because of its unique and distinct properties like Mott metal-to-insulator transition,
giant magneto-resistance, superconductivity. While the density functional theory
(DFT), the standard approach to electronic band calculations, is able to describe
properties of weakly correlated systems but is known to have serious limitation in the
description of strongly correlated systems, the dynamical mean field theory (DMFT) has
become an established method for the treatment of strongly correlated systems. In this
dissertation, we study the properties of correlated electronic systems near Mott metalto-
insulator transitions using DMFT, which maps Hubbard like lattice model in infinite
coordination number to a single site impurity Anderson model with the self-consistent
conditions. We implement the continuous-time hybridization expansion (CT-HYB)
version of continuous-time quantum Monte Carlo (CT-QMC) for the impurity model
to investigate the Mott metal-to-insulator in the Hubbard model on Bethe lattice
without symmetry braking. At half filling a gap opening transition is found to occur
as the interaction strength is increased beyond critical value. We extend our analysis
to the inclusion of retarded interaction (electron-phonon interaction) in the frame
work of Hubbard-Holstein model. We implement the CT-HYB in the presence of
retarded interaction for the impurity model. The effect of the inclusion of retarded
interaction to Hubbard model is to shift the Mott metal-to-insulator to a large critical
values as compared to the pure Hubbard model. The interplay of electron-electron and
electron-phonon interaction near the Mott metal-to-insulator transition are discussed
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The Study of Strongly Correlated