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Showing 1 to 20 of 20 for “"Valence Bond"”.
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A valence bond for several perturbations
A valence bond perturbation method is developed for the purpose of treating the pi electron spectra of molecules related to a parent conjugated hydrocarbon molecule. A spectral perturbation reflects the change in pi electron transition energy of the parent hydrocarbon as a result of heteroatom …
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Applications of Valence Bond Theory to Problems in Magnetic Resonance
Made available in DSpace on 2014-12-05T19:37:38Z (GMT). No. of bitstreams: 1 6100199.pdf: 5604822 bytes, checksum: 968e8f7b3403e8d9db52a03fb7152c55 (MD5) Previous issue date: 1960
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Dual mappings and phase transitions in a short-range random valence bond theory
… calculations done in 3-D Short-Range Random Valence Bond theory. After reviewing the background of SRRVB and how it can be derived, I cover the technique of dual mappings, with a particular emphasis on the Compact U(1) model, the monopole loop gas picture, and the confinement/deconfinement …
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Theoretical and computational investigations of the electron and spin correlation in chemical bonds, building a predictive bonding model with generalized valence bond theory
… is to understand the nature of chemical bonds. By understanding the underlying physical and chemical principles of chemical bonding in various molecules, chemists can make predictions about the structures, energetics, reactivities and other properties of chemical species. The …
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The Physico-chemical Nature of the Chemical Bond: Valence Bonding and the Path of Physico-chemical Emergence
… of quantum mechanics to the problem of chemical bonding by physicists and chemists, formed the chemical bond into a physico-chemical theory. In the late nineteenth-century context of early physical chemistry, the chemical bond was known as a physical link between atoms, which could not be studied …
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Variational study of strongly correlated electronic models
… 1987, P.W. Anderson proposed that a resonating valence bond (RVB) wave-function, which consists of a superposition of valence-bond states, contains the ingredients to account for a consistent theory of the Hubbard and t−J models. Motivated by the success of variational Monte- Carlo to describe …
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Computing the energetic component of the charge-transfer symmetry factor
… classical model consists of two empirical valence bond states and a control parameter that effectively determines the reaction free energy. The model mimics an outer-sphere electron-transfer reaction that obeys Marcus theory to a good approximation. This theory uses the energy difference …
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Composition dependence of superconductivity in YBa₂(Cu<sub>1-x</sub>A<sub>x</sub>)₃O<sub>6+δ</sub> system with A = Zn, Ni
… impurities and in terms of the Resonance Valence Bond model proposed by Anderson.
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Approximate Spin Extended Hartree-Fock theory
… a qualitatively acceptable description of bond dissociation, correctly predicts the symmetry of molecular states where RHF theory fails, and provides an efficient means for obtaining a significant amount of correlation energy in molecular calculations. Moreover, when the Generalized Valence …
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General method for the development of models of electronic structure and bonding: covalent bonds, recoupled pair bonds and through-pair interactions
The concept of the chemical bond is essential to our understanding of molecular phenomena. G. N. Lewis laid the groundwork for our understanding of chemical bonds nearly a century ago in his classic 1916 paper in the Journal of the American Chemical Society, “The Atom and the Molecule.” This model …
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Wonderland of frustration: Magnetic moments and itinerant electrons on the pyrochlore lattice
… particularly, the long sought-after resonating valence bond spin liquid originally proposed by Anderson. We prove that the resonating valence bond spin liquid is the ground state of the infinite-U Hubbard model in the thermodynamic limit. Based on numerical computations, we find the result also …
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Theoretical studies of the bonding, energetics and spectra of sulfur and phosphorus halides, and reactivity of divalent sulfur compounds: impact of recoupled pair bonding
… (n=2-4)—are presented in this dissertation. The bonding in the ground and excited states of these species was analyzed using generalized valence bond theory. These (and other) studies have led to a model—the recoupled pair bond (RPB) model—that provided much insight into the electronic structure …
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Terahertz spectroscopy of quantum spin liquids
… even at 0 K, instead giving way to a Resonating Valence Bond state. Quantum Spin Liquids host exotic fractionalized excitations called spinons, which carry spin 1/2 but no charge. The low-energy behavior of these excitations are proposed to be governed by emergent gauge fields that depend on the …
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Strategies for the synthesis of bioactive compounds: biomimetic approaches to the Salinosporamides and the hexadehydro-Diels-Alder reaction
… with their mesoionic Münchnone forms. Valence bond isomerism interconverts Münchnones to amidoketenes. Spontaneous ketene-ketone [2+2] cycloaddition would siphon the precursors through such a tautomeric manifold to give the natural product. Progress toward the synthesis of the …
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Insights into the chemistry of sulfur-containing molecules
In this dissertation, we utilize generalized valence bond (GVB) theory and the recoupled pair bonding model in order to understand the chemical bonding in a variety of sulfur-containing molecules. We use the resulting insights to rationalize experimental and computational results as well as to make …
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Correlação eletrônica e magnetismo em sistemas quase - unidimensionais
… fases antes de atingir um estado RVB (resonating valence bond) de curto alcance com gap de spin e isolante em ? =1/3. Finalmente, para ?>1/3, observamos um cruzamento (crossover), que antecipa o comportamento líquido de Luttinger encontrado para ?>2/3. Finalmente, tratamos o efeito de frustração …
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X-ray crystallographic studies on the self-condensation products of o-aminobenzaldehyde and anthranilic acid and of the metal complexes of some related tetra-azamacrocycles.
… salts the anion appears to be doubly hydrogen bonded to the cation, through hydrogen donors NH and CH. The results enable a controversy in the literature regarding the structures of these compounds to be resolved. The self-condensation products of anthranilic acid, AA, also somewhat …
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On numerical methods in quantum spin systems
… is discussed using the example of Resonance Valence Bond (RVB) state, which serves as a qualitative exemplification of spin liquid phases. I discuss means of detecting phase transitions with a focus on methods that are applicable in a numerical setting. Chapter 3 presents elements of the …
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Embedded-fragment studies of ice, water, and molecular cluster cations
… computationally observed and linked to hydrogen bond-bending acoustic phonons that soften with increasing pressure. The anomalous volume isotope effect, where D2O possesses a larger molar volume than H2O ice, was determined to be a more complex phenomenon relying on cancellations between …
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Coupled one dimensional electron systems and stripe phases of high temperature superconductors
… PDW phase appears even at weak coupling when the bonding band of the ladder is half filled. This state is shown to be dual to a uniform superconducting (SC) phase with quasi long range order. By making use of bosonization and the renormalization group, the phase diagram of the spin-gapped regime …