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Improved Partial Charge Models in Siliceous Zeolites for the Simulation of Adsorption and Identification of Catalytic Sites UNLV Theses, Dissertations, Professional Papers, and Capstones August 2017 Improved Partial Charge Models in Siliceous Zeolites for the Simulation of Adsorption and Identification of Catalytic Sites Jarod J. Wolffis University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/thesesdissertations Part of the Inorganic Chemistry Commons, and the Quantum Physics Commons Repository Citation Wolffis, Jarod J., "Improved Partial Charge Models in Siliceous Zeolites for the Simulation of Adsorption and Identification of Catalytic Sites" (2017). UNLV Theses, Dissertations, Professional Papers, and Capstones. 3107. http://dx.doi.org/10.34917/11156845 This Thesis is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Thesis has been accepted for inclusion in UNLV Theses, Dissertations, Professional Papers, and Capstones by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. IMPROVED PARTIAL CHARGE MODELS IN SILICEOUS ZEOLITES FOR THE SIMULATION OF ADSORPTION AND IDENTIFICATION OF CATALYTIC SITES By Jarod J. Wolffis Bachelor of Science – Chemistry University of Nevada Las Vegas 2013 A thesis submitted in partial fulfillment of the requirements for the Master of Science – Chemistry Department of Chemistry and Biochemistry College of Sciences The Graduate College University of Nevada, Las Vegas August 2017 Thesis Approval The Graduate College The University of Nevada, Las Vegas July 27, 2017 This thesis prepared by Jarod J. Wolffis entitled Improved Partial Charge Models in Siliceous Zeolites for the Simulation of Adsorption and Identification of Catalytic Sites is approved in partial fulfillment of the requirements for the degree of Master of Science – Chemistry Department of Chemistry and Biochemistry Paul Forster, Ph.D. Kathryn Hausbeck Korgan, Ph.D. Examination Committee Chair Graduate College Interim Dean Kathleen Robins, Ph.D. Examination Committee Member Keith Lawler, Ph.D. Examination Committee Member Carryn Warren, Ph.D. Graduate College Faculty Representative ii Abstract Utilization of computational modelling and simulation is expanding as computer processing power has increased and as new tools have been developed. This thesis focuses on efforts to improve the accuracy of simulations in aluminosilicate zeolites, an industrially important category of materials for catalysis and separations. For these sorbents, partial atomic charge represents a critical parameter in molecular mechanics simulations, determining the Coulombic non-bonding interaction. Partial charges may also be used as a measure of important physical parameters of the system such as the degree of covalency or the relative acidity of catalytic sites. We compare several common methods for predicting partial atomic charges in siliceous (pure silica) zeolites, analyze the geometric dependence of these charges, and we test if that data can be used to predict the site for tetrahedral atom substitution in the synthesis of catalytically active zeolites. In addition, we test the partial atomic charges for their ability to predict N2 and O2 adsorption with common dispersion-repulsion parameterizations. A second project is also described where detailed first-principles analysis of a pentanuclear technetium iodide structure was conducted in the solid state. We utilized spin polarization in DFT to test the average magnetic moment and sought further explanation using the structures density of states and electronic band structures. iii Acknowledgements This thesis is dedicated to my family and friends, I wouldn’t be here if not for you. Thank you. I would like to express my deepest gratitude to my supervisors Keith Lawler and Professor Paul Forster for their unwavering support, collegiality, and mentorship throughout this project. I would like to extend additional thanks to those who offered collegial guidance and support over the years: Professor Kathleen Robins, Professor David Hatchett, Professor MaryKay Orgill, Professor Larry Tirri, and Professor Jennifer Guerra. iv To those who continue to struggle to reach their goals, may you find success in what inspires you, may you reach for the unreachable, may you bear the unbearable. v Table of Contents Abstract ...................................................................................................................................................... iii Acknowledgements .................................................................................................................................... iv List of Tables ........................................................................................................................................... xiii List of Figures ............................................................................................................................................. x Chapter 1: Introduction ............................................................................................................................... 1 1.1: Density Functional Theory ............................................................................................................. 1 1.1.1: Schrödinger Equation .................................................................................................................. 1 1.1.2: Hohenberg – Kohn Theorem ....................................................................................................... 5 1.1.3: Kohn Sham .................................................................................................................................. 7 1.1.4: LDA’s, GGA’s, Meta GGA’s, Hybrids and Dispersions ............................................................ 9 1.2: Partial Charge Methods ................................................................................................................ 15 1.2.1: Semi-Empirical Techniques ....................................................................................................... 15 1.2.2: Ab Initio Techniques .................................................................................................................. 17 1.3: Sampling Thermodynamic Properties with Monte Carlo ............................................................. 20 1.4: Zeolites, a Brief Introduction ........................................................................................................ 24 Chapter 2: Predicting Partial Charges in Siliceous Zeolites ..................................................................... 27 2.1: Introduction .................................................................................................................................. 27 2.2: Methods ....................................................................................................................................... 31 2.2.1: Simulation ................................................................................................................................. 31 2.2.2: Experimental ............................................................................................................................. 33 2.3: Results and Discussion ................................................................................................................ 34 2.3.1: Comparing Charge Mythologies ............................................................................................... 34 2.3.2: The Relationship Between Acidic/Catalytic Sites and Partial Atomic Charges ....................... 36 2.3.3: The Effect of Compression on Partial Atomic Charges ........................................................... 44 vi 2.3.4: Performance in Predicting Gas Adsorption .............................................................................. 47 2.4: Conclusions .................................................................................................................................. 51 Appendix A ............................................................................................................................................... 54 A New Binary Halide Structure Type; Pentanulclear Technetium Iodide, Tc5I13 .............................. 54 Appendix B ............................................................................................................................................... 55 References ................................................................................................................................................. 79 Curriculum Vitae ...................................................................................................................................... 88 vii List of Tables Table 1 - A summary of the partial atomic charge determination methods used in this work ................. 30 Table 2 - A comparison of the partial charges determined with several methodologies for the IZA-SC structure of BEA............................................................................................................................................................................ 35 Table 3 - A comparison
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