Access Type

Open Access Dissertation

Date of Award

January 2023

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Chemistry

First Advisor

H. Bernhard Schlegel

Abstract

Strong field electron dynamics are a quickly developing field of study in physical chemistry. In order to better understand experimental observations, there is a need for computational tools to simulate electron dynamics in a strong field. Due to the nature of strong electric fields, this requires the solving of the time dependent Schrödinger equation (TDSE). Various methods have been used to solve the TDSE in a strong field. In order to look at molecular systems while accurately treating the underlying physics, a method that balances computational affordability with theoretical rigor is necessary. The chosen method that matches these criteria is time dependent configuration interaction with a complex absorbing potential (TDCI-CAP). This thesis discusses the use of the TDCI-CAP method in the study of strong field dynamics as well as various extensions made to the method. These extensions to the method allow for the study of more systems and comparison with different types of experiment. Extensions of the TDCI-CAP method are covered in Chapters 2, 3, 4, 6, 8, and 9. Chapter 2 discusses simulations using circularly polarized light. Chapters 3 and 4 look at the use of TDCI-CAP for atoms up to iodine and explore the angular dependence of ionization for methyl halides and haloacetylenes. Chapter 6 investigates molecular nitrogen, where Hartree Fock methods fail and density functional theory is required to accurately treat the angular dependence of ionization. Chapter 8 covers the addition of the spin-orbit coupling effect to the TDCI-CAP method, which is necessary for heavier atoms where relativistic effects can have a large impact. The final extension of the method is sequential double ionization, an important process in over the barrier ionization, is discussed in Chapter 9. Applications of the TDCI-CAP method are covered in Chapters 5, 7, and 10. Chapter 5 is a collaborative study with the Li group looking at the electronic dynamics of methyl iodide using angular streaking. Chapter 7 investigates the possibility of directly ionizing PENNA to a superposition of cation states due to the potential for charge migration. Chapter 10 discusses the electronic wavepackets in krypton and xenon in collaboration with the Li group. Finally, Chapter 11 looks at a future extention to the TDCI-CAP method that would decrease the computational cost of the method, allowing for the simulation of larger systems.

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