Subject Area
Chemistry
Abstract
Electronic structure provides a fundamental framework for understanding molecular properties and reactivity, as it encodes the spatial distribution of electrons and their response to external and internal perturbations. This dissertation develops theoretical and computational frameworks to characterize and manipulate electronic structure through two complementary directions: the response to oriented external electric fields and the quantification of symmetry regulation in electron density.
First, a rigorous theoretical and computational framework is established for treating electric fields with arbitrary orientations relative to molecular structure. The concept of the rotational potential energy surface is introduced to characterize the dependence of molecular energy on field direction. By defining electric fields in molecule-fixed coordinate systems, including principal axis and local reference frames, consistent field orientations are maintained during structural changes. Analytic nuclear gradients that incorporate field-orientation coupling are derived and implemented, enabling efficient and stable geometry optimizations under oriented electric fields. These developments extend conventional aligned-field approaches and provide a systematic means to probe and control molecular structure and reactivity.
Second, a density-based framework for quantifying electronic structure distortion from a symmetry perspective is developed. An algorithm for computing local continuous symmetry and chirality directly from the electron density is introduced, allowing quantitative characterization of symmetry breaking in complex systems. These measures capture chemically meaningful features of local environments and are applied to analyze reactivity patterns and chiral recognition, demonstrating their utility in connecting electronic structure to observable chemical behavior.
Together, these advancements establish a unified perspective on electronic structure distortion. This work provides a comprehensive framework for understanding and directing molecular transformations through both external-field control and intrinsic symmetry analysis.
Degree Date
Spring 5-16-2026
Document Type
Dissertation
Degree Name
Ph.D.
Department
Chemistry
Advisor
Devin Matthews
Number of Pages
144
Format
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License
Recommended Citation
Lai, Duc Anh, "Ab initio Method Development for Electronic Structure Response and Symmetry Quantification" (2026). Chemistry Theses and Dissertations. 60.
https://scholar.smu.edu/hum_sci_chemistry_etds/60
Included in
