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Physical Sciences and Mathematics Commons

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Full-Text Articles in Physical Sciences and Mathematics

Towards A Unification Of Supercomputing, Molecular Dynamics Simulation And Experimental Neutron And X-Ray Scattering Techniques, Benjamin Lindner Dec 2012

Towards A Unification Of Supercomputing, Molecular Dynamics Simulation And Experimental Neutron And X-Ray Scattering Techniques, Benjamin Lindner

Doctoral Dissertations

Molecular dynamics simulation has become an essential tool for scientific discovery and investigation. The ability to evaluate every atomic coordinate for each time instant sets it apart from other methodologies, which can only access experimental observables as an outcome of the atomic coordinates. Here, the utility of molecular dynamics is illustrated by investigating the structure and dynamics of fundamental models of cellulose fibers. For that, a highly parallel code has been developed to compute static and dynamical scattering functions efficiently on modern supercomputing architectures. Using state of the art supercomputing facilities, molecular dynamics code and parallelization strategies, this work also …


Laser-Atom Interactions: A Multiresolution Approach, Nicholas Eric Vence May 2012

Laser-Atom Interactions: A Multiresolution Approach, Nicholas Eric Vence

Doctoral Dissertations

Isolated, attosecond laser pulses have allowed real-time measurement and control of electrons on atomic time scales. We present an explicit time-evolution scheme solving the time dependent Schro ̈dinger equation, which employs an adaptive, discontinuous, spectral-element basis that automatically refines to accommodate the requested precision providing efficient computation across many length scales in multiple dimensions. This method is illustrated through time evolution studies of single electron atoms and molecular ions in three and four dimensions under the influence of intense, few-cycle laser pulses.


Atomistic Simulations Of The Fusion-Plasma Material Interface, Mostafa Jon Dadras May 2012

Atomistic Simulations Of The Fusion-Plasma Material Interface, Mostafa Jon Dadras

Doctoral Dissertations

A key issue for the successful performance of current and future fusion reactors is understanding chemical and physical processes at the Plasma Material Interface (PMI). The material surfaces may be bombarded by plasma particles in a range of impact energies (1 eV - a few keV) and kept at a range of temperatures (300 - 1000 K). The dominant processes at the PMI are reflection and retention of impacting particles and sputtering (chemical and physical). Sputtering leads to surface erosion and pollution of the plasma, both of which degrade reactor performance. Retention influences the recycling of the plasma, and in …