Application of quantum force computations for Raman spectroscopy and molecular dynamics

dc.contributor.advisorChelikowsky, James R.
dc.creatorNeitzel, Joshua Clark
dc.date.accessioned2019-12-02T16:55:10Z
dc.date.available2019-12-02T16:55:10Z
dc.date.created2019-08
dc.date.issued2019-08-16
dc.date.submittedAugust 2019
dc.date.updated2019-12-02T16:55:11Z
dc.description.abstractElectronic structure calculations have undergone incredible advancement in the past century. Using modern methods and supercomputing infrastructure we are now able to compute precise electron behavior in a variety of large and complex systems. However, these computations are only as good as their applications. To further these computations we consider two applications of efficient force calculations using first principles density functional theory. We compute the vibrational and Raman spectra for B-doped, P-doped, and B-P codoped Si nanocrystals using real-space pseudopotentials constructed within density functional theory. An experimental peak in the Raman spectra near 650 cm⁻¹ observed in codoped nanocrystals can be best explained by the presence of B-P bonds, which are located near the surface of the nanocrystal. We propose that the spectral details of this peak are related to quantum confinement and the breaking of local symmetry associated with the phonon modes involving dopant bonds. We also illustrate an improved method for calculation of nonlocal contributions to interatomic forces is used to perform molecular dynamics simulations. This method results from the real space density functional theory Hamiltonian utilizing a high order Gaussian integration scheme in real space. The efficacy of this method is demonstrated through molecular dynamics simulations of an O₂ molecule and a benzene molecule. Our method improves convergence of dynamic variables including stability and vibrational frequency
dc.description.departmentPhysics
dc.format.mimetypeapplication/pdf
dc.identifier.urihttps://hdl.handle.net/2152/78614
dc.identifier.urihttp://dx.doi.org/10.26153/tsw/5670
dc.language.isoen
dc.subjectDFT
dc.subjectComputational physics
dc.subjectMaterials design
dc.subjectRaman spectroscopy
dc.subjectMolecular dynamics
dc.subjectQuantum force
dc.titleApplication of quantum force computations for Raman spectroscopy and molecular dynamics
dc.typeThesis
dc.type.materialtext
thesis.degree.departmentPhysics
thesis.degree.disciplinePhysics
thesis.degree.grantorThe University of Texas at Austin
thesis.degree.levelMasters
thesis.degree.nameMaster of Arts

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