TOTALLY EMPIRICAL WAVEFUNCTIONS FROM X-RAY DIFFRACTION DATA (QUANTUM MECHANICS, ELECTRON DENSITY).
Item
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Title
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TOTALLY EMPIRICAL WAVEFUNCTIONS FROM X-RAY DIFFRACTION DATA (QUANTUM MECHANICS, ELECTRON DENSITY).
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Identifier
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AAI8501131
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identifier
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8501131
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Creator
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GOLDBERG, MARTIN JEFFRY.
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Contributor
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Louis J. Massa
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Date
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1984
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Physical
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Abstract
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The interpretation of coherent x-ray diffraction experiments by a quantum model is described. Adjusting the coefficients of an LCAO expansion to best fit measured Bragg intensities results in a totally empirical quantum wavefunction. The quantum model is compared to a multipole expansion. The constraints imposed by quantum mechanics are examined, and several methods of satisfying these constraints while best fitting a wavefunction to measured Bragg intensities are detailed. Application is made to beryllium metal, with a resultant fit R(,1) = .00249. Similar applications to graphite and diamond are outlined. The formalism is extended to explicitly include solid-state effects, and this extension is applied to a model problem of an infinite line of hydrogen atoms. Neglect of solid-state effects can lead to errors of as much as 1% per electron. A more realistic treatment of crystal vibrations using a TLS model for external motions and 3N-6 spectroscopic-like local modes for internal motions is suggested. Related numerical algorithms are displayed. Directions for future work are suggested.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
