Lithium halide structural chemistry : computational analysis with machine learning, quantum chemistry, and molecular dynamics
department or school: Science, Faculty of
department or school: Chemistry, Department of
data provider: DSpace
degree campus: UBCV
creator: Scheiber, Hayden Owen
issued: 2022-12-22T09:04:52Z
issued: 2022
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: The lithium halide salts may at first appear to be simple chemical systems. However, previous research indicates lithium halides have complex and poorly understood crystallization pathways from aqueous solutions. While lithium halides exist in the rocksalt crystal structure under ambient conditions, common lithium halide classical force fields more often predict wurtzite as the stable structure. This failure severely limits their application in molecular simulations of crystallization. Research in this thesis focuses on presenting new results and computational methodology to better understand the structural chemistry of both lithium halides and alkali halides in general. Density functional theory together with classical force fields are employed to examine the relative stability of candidate crystal structures for lithium halides and produce accurate theoretical reference data. Dispersion interactions are shown to play a key role in the stability of rocksalt over closely competing crystal structures. Classical models can be corrected in their structural predictions by scaling up the strength of dispersion, indicating a pathway towards better lithium halide force fields. Convolutional neural networks are used for the structural classification of simulated alkali halides. The neural networks are trained on a large data set generated from molecular dynamics simulations of alkali halides across a range of temperatures. Time convolution filters out short-lived structural fluctuations. The structure classifiers are shown to be accurate in bulk phase simulations, then demonstrated on crystallization of model alkali halide systems from the melt. The neural network classifiers are implemented in a melting point calculation algorithm for model binary salts. Finite size effects are characterized, then melting points of alkali halides using common rigid-ion interaction potentials are calculated and discussed. The methods developed throughout the research are employed for the op…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/83478
note: Lithium Halide Structural ChemistryComputational Analysis with Machine Learning, Quantum Chemistry, andMolecular DynamicsbyHayden Owen ScheiberA THESIS SUBMITTED IN PARTIAL FULFILLMENTOF THE REQUIREMENTS FOR THE DEGREE OFDoctor of PhilosophyinTHE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES(Chemistry)The University of British Columbia(Vancouver)December 2022© Hayden Owen Scheiber, 2022The following individuals certify that they have read, and recommend to the Faculty of Graduateand Postdoctoral Studies for acceptance, the thesis entitled:Lithium Halide Structural ChemistryComputational Analysis with Machine Learning, Quantum Chemistry, and Molecular Dynamicssubmitted by Hayden Owen Scheiber in partial fulfillment of the requirements for the degree ofDoctor of Philosophy in Chemistry.Examining Committee:Gren N. Patey, Professor, Chemistry, UBCSupervisorKeng Chou, Professor, Chemistry, UBCSupervisory Committee MemberMark Thachuk, Associate Professor, Chemistry, UBCSupervisory Committee MemberYan Alexander Wang, Associate Professor, Chemistry, UBCSupervisory Committee MemberEd R. Grant, Professor, Chemistry, UBCUniversity ExaminerJoerg Rottler, Professor, Physics and Astronomy, UBCUniversity ExaminerRichard Bowles, Professor, Chemistry, University of SaskatchewanExternal ExamineriiAbstractThe lithium halide salts may at first appear to be simple chemical systems. However, previousresearch indicates lithium halides have complex and poorly understood crystallization pathwaysfrom aqueous solutions. While lithium halides exist in the rocksalt crystal structure under ambientconditions, common lithium halide classical force fields more often predict wurtzite as the stablestructure. This failure severely limits their application in molecular simulations of crystallization.Research in this thesis focuses on presenting new results and computational methodology to betterunderstand the structural chemistry of both lithium halides and alkali halides in general.Density functional t…
has type: Thesis/Dissertation
date issued: 2023-05
is shown at: 10.14288/1.0422779
language: eng
degree discipline: Chemistry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc/4.0/
scholar level: Graduate
contributor: Patey, Grenfell
type: Text
type: Moving Image
identifier URI: http://hdl.handle.net/2429/83478