자료유형  

 학위논문

Control Number  

0016931486

International Standard Book Number  

9798379707866

Dewey Decimal Classification Number  

530

Main Entry-Personal Name  

Pandey, Bipul.

Publication, Distribution, etc. (Imprint  

[S.l.] : The University of Chicago., 2023

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2023

Physical Description  

1 online resource(149 p.)

General Note  

Source: Dissertations Abstracts International, Volume: 84-12, Section: B.

General Note  

Advisor: Littlewood, Peter B.

Dissertation Note  

Thesis (Ph.D.)--The University of Chicago, 2023.

Restrictions on Access Note  

This item must not be sold to any third party vendors.

Summary, Etc.  

요약Electrons in materials undergo numerous complex interactions among themselves, the external fields, as well as the constituent atomic lattice. The strength of such many-body interactions depends on various factors such as the electronic configuration of the host material, the presence of doping and defects, spins of carrier and lattice elements, etc. In the thermodynamic limit, these interactions are often treated as bosons that interact with the electrons in the system and manifest as side bands (replicas or satellites) in the electronic band structure seeping spectral weight and renormalizing the band structure obtained from purely electronic calculations.In ab-initio calculations, when the strength of such electron-boson interaction is weak, it is not only justified to neglect these interactions completely but also pragmatic for reasons ranging from tractability to associated computational cost. This is because the effect of electron-boson interaction is minute compared to the electronic energy scale of the problem. However, in many systems, especially organic semiconducting materials, the bosonic vibrations (stretching modes) of the molecule are strongly coupled with the electron. Furthermore, the bosonic energy scale is comparable to the electronic energy scale in these problems. Hence, neglecting the effect of electron-boson interactions in electronic spectra in such systems is myopic at best and catastrophic at worst.In the context of a single electron two orbital Holstein system coupled to dispersionless bosons, we develop a general method to correct single-particle Green's function and electronic spectral function using an integral power series correction (iPSC) scheme. We then outline the derivations of various flavors of cumulant approximation through the iPSC scheme and explain the assumptions and approximations behind them. Finally, we compute and compare iPSC spectral function with cumulant and exact diagonalized spectral functions and elucidate three regimes of this problem - two that cumulant explains and one where cumulant fails. We find that the exact and the iPSC spectral functions match within spectral broadening across all three regimes.In order to scale our method to large systems, we then develop an ODE-based Power series correction(dPSC) formalism that goes beyond the cumulant approximation. We implement it to a 1D Holstein chain for a wide range of coupling strengths in a scalable and inexpensive fashion at both zero and finite temperatures. We show that this first differential formalism of the power series is qualitatively and quantitatively in excellent agreement with exact diagonalization results on the 1D Holstein chain with dispersive bosons for a large range of electron-boson coupling strength. We also investigate carrier mass growth rate and carrier energy displacement across a wide range of coupling strengths. We also present a faster second differential formalism which is very much similar to self-consistent cumulant formalism. We show the regime where this method is applicable and where it diverges. Finally, we present a heuristic argument that predicts most of the rich satellite structure without explicit calculation.

Subject Added Entry-Topical Term  

Physics.

Subject Added Entry-Topical Term  

Theoretical physics.

Subject Added Entry-Topical Term  

Computational physics.

Subject Added Entry-Topical Term  

Atomic physics.

Index Term-Uncontrolled  

Band structure

Index Term-Uncontrolled  

Cumulant

Index Term-Uncontrolled  

Electron-boson interaction

Index Term-Uncontrolled  

Green's function

Index Term-Uncontrolled  

Holstein Hamiltonian

Index Term-Uncontrolled  

Molecular crystal

Added Entry-Corporate Name  

The University of Chicago Physics

Host Item Entry  

Dissertations Abstracts International. 84-12B.

Host Item Entry  

Dissertation Abstract International

Electronic Location and Access  

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Control Number  

joongbu:643604