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dc.contributor.authorYan, Ge
dc.description.abstractModern quantum mechanical theories, including high-level ab initio methods and density functional theory, have been applied to a variety of molecular systems. The first work performs a comprehensive anharmonic vibrational analysis of propargyl radical. A highly-accurate quartic force field was constructed with coupled-cluster including singles and doubles and perturbatively applied triple excitations [CCSD(T)] using the aug’-cc-pVTZ basis set, complemented with a quadratic force field extrapolated to the complete basis set limit using cc-pVXZ (X=T, Q, 5) basis sets. Fundamental vibrational frequencies were computed with the complete quartic force field based on vibrational perturbation theory. In the second work, accurate electron affinities and ionization potentials of trans- and cis-hydroxyformyl radicals were determined via systematic ab initio investigations. State-of-the-art ab initio electronic structure theories combined with aug-cc-p(C)VXZ (X=2-6) basis sets were utilized to extrapolate to the complete basis set full configuration interaction limit via the focal point analysis method. Core-correlation effects, special relativity, zero-point vibrational energy, and diagonal Born-Oppenheimer corrections were explicitly incorporated in the results to -1provide accuracy to the level of 0.1 kcal mol. The last work examines optimal structures, energetics, and harmonic vibrational frequencies of adamantane and a variety of its derivatives using four different density functional methods and the DZP++ basis set. Electronic affinities, ionization potentials and other properties have been predicted.
dc.subjectab initio Method
dc.subjectCoupled-cluster Theory
dc.subjectDensity Functional Theory
dc.subjectQuartic Force Field
dc.subjectPropargyl Radical
dc.subjectElectron Affinity
dc.subjectIonization Potential
dc.subjectHydroxyformyl Radical
dc.titleApplications of modern quantum mechanical theories
dc.title.alternativefrom propargyl and hydroxyformyl radicals to adamantane
dc.description.advisorHenry F. Schaefer, III
dc.description.committeeHenry F. Schaefer, III
dc.description.committeeNigel G. Adams
dc.description.committeeGeoffrey D. Smith

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