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Full-Text Articles in Engineering Science and Materials
Development Of Density-Functional Tight-Binding Methods For Chemical Energy Science, Quan Vuong
Development Of Density-Functional Tight-Binding Methods For Chemical Energy Science, Quan Vuong
Doctoral Dissertations
Density-functional tight-binding (DFTB) method is an approximation to the popular first-principles density functional theory (DFT) method. Recently, DFTB has gained considerable visibility due to its inexpensive computational requirements that confer it the capability of sustaining long-timescale reactive molecular dynamics (MD) simulations while providing an explicit description of electronic structure at all time steps. This capability allows the description of bond formation and breaking processes, as well as charge polarization and charge transfer phenomena, with accuracy and transferability beyond comparable classical reactive force fields. It has thus been employed successfully in the simulation of many complex chemical processes. However, its applications …
Energy Selective Neutron Imaging For The Characterization Of Polycrystalline Materials, Robin Woracek
Energy Selective Neutron Imaging For The Characterization Of Polycrystalline Materials, Robin Woracek
Doctoral Dissertations
This multipart dissertation focuses on the development and evaluation of advanced methods for material testing and characterization using neutron diffraction and imaging techniques. A major focus is on exploiting diffraction contrast in energy selective neutron imaging (often referred to as Bragg edge imaging) for strain and phase mapping of crystalline materials. The dissertation also evaluates the use of neutron diffraction to study the effect of multi-axial loading, in particular the role of applying directly shear strains from the application of torsion. A portable tension-torsion-tomography loading system has been developed for in-situ measurements and integrated at major user facilities around the …