Power structures in U.S. public schools have grown increasingly more hierarchical in response to a perceived decline in K-12 instructional quality. The rising prominence of high-stakes accountability mechanisms has resulted in top-down limiting of teachers' role in site decision-making. Promoting a more prominent teacher role in school governance is a promising countermeasure to the teacher turnover and lower quality of instruction disproportionately found in schools serving vulnerable populations. When educators have a greater voice in site decision-making, they are more committed to the organizational vision and more likely to stay at a school. Student academic and civic outcomes also improve when school governance is democratically collaborative. Recognizing the need for additional research on the relationship between decision-making authority and the role of teachers in site governance at an educator-run school, one site was examined through a qualitative, case study approach using an integrated theoretical framework that incorporated structure, culture and agency and the areas of collective autonomy exploring (1) the role of teachers in site governance at an educator-run school and (2) the structural and cultural systems that support or hinder teachers' role in site decision-making.

Qualitative data compiled through interviews, observations of decision-making meetings and gathering of site documents clarified how structural and cultural systems shape and are shaped by teachers’ participation in site decision-making. Analysis of the themes and categories that surfaced from the data shed light on the relationship between formal, prescribed decision-making authority and the dynamics of educator-run school governance in practice.

Findings from the study indicated that systems that hinder teachers’ participation in school governance are legal, district and budget constraints, lack of preparation and mistrust. Governing documents that support significant teachers’ role in school-level decisions are the pilot school agreement and Elect-to-Work Agreement with its annual teacher-driven revisiting and refinement. Representative leadership, rotating leadership and protocols help to democratize decision-making at the research site by providing transparent structures to guide selection of leaders and horizontal collaboration. Cultural systems that support significant teachers’ role in school-level decisions are a common vision, collaboration, sense of ownership, peer accountability, mentoring and organizing skills.

The optical and electronic properties of semiconductor nanomaterials have long attracted significant interest due to the strong absorption and tunable spectra caused by quantum confinement. These materials have potential applications ranging from solar energy conversion and lighting to single photon sources and quantum computing. However, to realize any of these applications the role of the atomistic detail of these materials cannot be ignored. Understanding role of defects, traps, and structural distortion on the excited states of these materials remains a great challenge for modern computational science. Semiemperical pseudopotential models represent the leading way to understand the complexity of nanoscale systems in atomistic detail. In this dissertation we expand the applicability of these models to new materials where additional effects, like strong spin-orbit coupling must be considered. We also use these methods to help examine the dynamics of excited states in these nanomaterials, revealing the crucial roles of defects, distortions, and traps.

We develop a formulation of the semiempirical pseudopotential method that includes the effects of spin-orbit coupling and other nonlocal terms in the potential. By using a separable form of these non-local terms we maintain a favorable computational scaling and thus keep the ability to investigate nanomaterials of experimentally relevant sizes. We apply this method to lead halide perovskite nanocrystals (NCs), promising materials for solar energy conversion that are known for their strong spin-orbit coupling. The atomistic study of these systems allows for an understanding of how distortion of the NC structure impacted the exciton fine structure, determining that contrary to some suggestions the ground state exciton is a dark state.

The results of atomistic electronic structure methods also aid in developing kinetic models of excited state species in various nanomaterials. The dynamics of the transfer of holes from multi-excitonic II-VI NCs is explored as a competition between transfer, trapping, and non-radiative Auger recombination (AR). Pseudopotential calculations provide crucial insight in the AR rates and how those are impacted by the presence of trapped species. A similar kinetic model describing carrier recombination in few-layer black phosphorous is informed by density functional theory calculations of surface oxygen defects.

This dissertation shows both the expansion of the semiemperical pseudopotential method and the application of the method to inform studies of material properties and design principles. The combination of theoretical development and experimental collaboration shows the utility of these models to solve practical problems of broad scientific import. By expanding the applicability of these methods to new materials, these detail atomistic calculations can now be applied to even more experimentally relevant systems.