The overall objective of this thesis has been to develop accurate computational methods for the diffusion and adsorption of small gases in zeolites. Firstly, the effect of the zeolite framework flexiblity on the single component and binary diffusion of various gases were discussed. Results indicate that for tight fitting molecules the rigid framework approximation can produce order(s) of magnitude difference in diffusivities as compared to the simulations performed with a fully flexible framework. We proposed two simple methods in which the flexible structure of a zeolite is approximated as a set of discrete rigid snapshots. Both methods are orders of magnitude more efficient than the simulations with the fully flexible structure. Secondly, we use a combined classical and quantum chemistry based approach to systematically develop the force fields based on DFT calculations for interactions of simple molecules like CH4, N2, linear alkanes, and linear alkenes in zeolites. We used a higher level of theory known as the DFT/CC method to correct DFT energies that were used in the periodic DFT calculations to develop force fields. Our results show that DFT-derived force fields give good predictions of macroscopic properties like adsorption isotherms in zeolites. The force fields are transferrable across zeolites and hence can be further used to screen materials for different storage and separation applications.

American cities have only recently come of age in the global sense. Therefore, most of our land use regulations have emphasized greenfield development issues over those of a mature city. The next wave of city building is redensification. This thesis argues that modern day, Euclidian zoning needs to be replaced in order to make the case for a sustainable mix of residential diversity, density, and affordability. Conventional zoning relies on simplistic measures to regulate density and shape the form of neighborhoods. Initially used primarily as a way to make the field of planning appear scientific and rational, these measures do not create functionally flexible neighborhoods for the changing needs of the twenty first century. Urban spaces should be thought of as a language, composed of pieces that evolve with cultural norms. Zoning must evolve to reflect current societal values, with an emphasis on environmental issues, while meeting the needs of changing market structures if cities are ever to sustainably house their populous. Zoning's inflexibility towards cultural shifts uses antiquated assumptions to force contemporary city design into a regulatory straight jacket. Using case studies within the city of Los Angeles because of its history in side-by-side integration of single family homes with a range of residential densities and supportive commercial uses, the thesis investigates three primary questions. First, under what zoning ordinances did the Los Angeles neighborhoods evolve and what lessons in functionality can be taken from their design? Second, looking at both conventional zoning and newer, form-based regulatory techniques, how does zoning affect the variety of housing types available? And third, what would a flexible zoning framework, created to support the future development of an evolving regional urbanization process and a changing social demographic, look like?