Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 15 of 15 for “"Reaxff"”.
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Gradient-Based Optimization of ReaxFF Parameters Using Pytorch for the Study of Silica Precipitation
… process using reactive force-field method (ReaxFF). Despite being a classical force field, ReaxFF can achieve quantum chemical accuracy once the optimal potential coefficients are found. However, the fitting of ReaxFF parameters is a challenge due to the complex functional form of the …
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Development of a ReaxFF force field for glyphosate and investigation of its abiotic degradation pathways
A ReaxFF force field has been developed for the widely used herbicide glyphosate (GLP), which degrades in the environment via C-P and C-N bond dissociation. Depending on the specific reaction pathway, toxic or non-toxic metabolites may form, however, the factors that influence the selection or …
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Exploring chemical reaction complexity : application to hydrogen combustion
… the presently available reactive force field, ReaxFF. We focus on developing computational and theoretical methods to analyze CMD simulations of hydrogen combustion and glean the details of chemistry to identify major sequential elementary reactions connecting reactants to products. In Chapter …
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Performance Engineering of Reactive Molecular Dynamics Simulations
… on-node parallelism. Current implementations of ReaxFF display good scaling across many distributed nodes, but fall short in taking full advantage of compute available on an individual CPU or GPU. This thesis presents analysis and performance optimization of the widely used LAMMPS ReaxFF …
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Structure and thermodynamics of solid/fluid interfaces: simulation and theory
… systems of industrial relevance. First, a new ReaxFF force field is developed to model silica-supported chromium catalysts. To this end, a new genetic algorithm optimization software is developed to allow global fitting of parameters for the newly developed force field. A proof-of-concept is …
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High Dimensional Non-Linear Optimization of Molecular Models
… data, and a reactive molecular dynamics (ReaxFF) model for oxygen and hydrogen. Each problem presents specific difficulties. The power and generality of the ParOpt software is illustrated by the successful optimization of such a diverse set of problems.
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Molecular Dynamic Simulation of Polysiloxane
… Molecular dynamics simulation paired with the Reaxff forcefield provides a framework to simulate the complex processes involved in pyrolysis such as chemical reactions and a combination of thermodynamic and kinetic interactions. This Thesis examines firstly the size effect that a system can …
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A molecular dynamics study of the tribological properties of diamond like carbon
… (MD) simulations with a reactive force field (ReaxFF) to study the friction and wear between DLC counterfaces, both in comparison to and in contact with steel counterfaces. We show that the tribological properties of DLC in dry sliding friction are heavily dependent on both the structure of the …
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Hierarchical and size dependent mechanical properties of silica and silicon nanostructures inspired by diatom algae
… the first principles based reactive force field ReaxFF, it is shown that when concurrent mechanisms occur, such as shearing and crack arrest, toughness is optimally enhanced. This occurs, for example, when structures encompass two nanoscale levels of hierarchy: an array of thin walled foil silica …
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Multi-paradigm modeling of mode I&II dynamic fracture mechanisms in single crystal silicon
… a novel first principles reactive force fields ReaxFF, which has shown to be an accurate model to describe fracture processes of silicon. Two numerical methods are used here to study fracture mechanisms in silicon: a multi-paradigm model employing reactive and non-reactive force fields, and a …
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Structure-property relationships from molecular simulation of polymeric matrix composites
… shape calculations. The final research area used ReaxFF simulations to study detailed reaction mechanisms and structure development resulting from carbonization of stabilized polyacrylonitrile (s-PAN). Higher oxygen content fibers promoted formation of CO and CO2 gases which lowered the final …
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Scale-bridging molecular dynamics simulations of plasma-surface interactions
… and its pyrolysis kinetics are determined using ReaxFF-based molecular dynamics (MD) simulations. Our MD simulations show that bulk pyrolysis starts at temperatures of ∼500 K, and exhibits a temperature dependence that follows the Arrhenius law. The pyrolysis process initiates with the removal of …