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Title: Novel quantum-based interatomic potentials applied to magnesium and its alloys
Author: Skinner, Guy Christopher Goodrich
ISNI:       0000 0004 8500 1300
Awarding Body: King's College London
Current Institution: King's College London (University of London)
Date of Award: 2019
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Metals have many desirable properties for industrial applications including strength, ductility and hardness. These and other mechanical properties are determined by the behaviour and interaction of crystal defects at the microscale. In order to make top-down predictions for novel alloy design with optimised mechanical properties, the energetics of crystal defects must be calculated with quantum-mechanical accuracy. Quantum-mechanical simulation takes many forms, as highlighted in Chapters 1 and 2, owing to the fact that a solution to the Schrödinger equation is computationally intractable for most systems. Density functional theory (DFT) is one such method which combines accuracy with efficient scaling. However, for the application of extended defects in metals, it is often unable to simulate the requisite number of atoms. This has led to the development of methods which combine the quantum-mechanical insight of DFT with the linear scaling of interatomic potentials. These methods are known as quantum-based interatomic potentials (QBIPs) and the focus of this thesis is the development of QBIPs for Magnesium and its alloys. In particular, we present work on the extension and application of the generalised pseudopotential theory (GPT). We develop the so-called adaptive GPT (aGPT) which resolves a discrepancy in the simple-metal limit of the GPT when applied to free surfaces and free volumes. The GPT formalism has also been applied to alloys, and this was used to generate interatomic potentials for the Magnesium-Calcium alloy system. These potentials were used to study phase stability in order to move towards a ductile Magnesium alloy.
Supervisor: Paxton, Anthony Thomas ; Van Schilfgaarde, Mark Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available