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Showing 1 to 20 of 106 for “"ab initio calculations"”.
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Ab initio Calculations of Optical Rotation
… cavity ringdown polarimetry data. When applicable, well-converged Gibbs free energy differences among confomers were determined using complete-basis-set extrapolations of CC energies in order to obtain Boltzmann-averaged specific rotations. The overall results indicate that the theoretical …
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Ab initio calculations of phonon properties and spectra in condensed matter
… variety of phonon properties. Our goal is to enable easy access to these phonon properties and to do this, we have developed a framework for easily automating the workflows involved in interfacing a phonon mode calculation with the analysis tools for determining such physical properties. This …
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Application of ab initio calculations to collagen and brome mosaic virus
In bio-related research, large proteins are of important interest. We study two such proteins. Collagen contains one such protein, the collagen triple-helix, which forms part of the structural matrix for animals, such as in their bones and teeth. 1JS9 is another protein that is a component of the …
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Ab initio calculations of NMR chemical shifts for structure determination in biology
… shift in the solid are studied by combinig ab initio molecular dynamics simulations and NMR chemical shift calculations. Other factors affecting the chemical shift are investigated by constructing ideal models from which we can extract information about the nature of the hydrogen bonds in …
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Ab initio calculations of the electronic properties of the nickel oxide surface
Self-consistent unrestricted Hartree-Fock calculations are presented for the adsorption of atomic oxygen onto the nickel oxide (100) surface. The perfect surface is shown to be non-reactive, but enhanced binding is found for vacancy sites in the first two atomic layers. Of particular interest are a …
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Ab Initio Calculations of the Electronic Properties of the Alumina and Silica Surfaces
Submitted by Jesse Garrison (jagarris@illinois.edu) on 2011-06-08T18:57:39Z No. of bitstreams: 1 1981_bedford.pdf: 1648762 bytes, checksum: 10cad360b8283d3aa937192b86e9c4b1 (MD5)
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Application of Ab Initio Calculations and Molecular Dynamics to Collagen and Brome Mosaic Virus
… interactions. In this thesis, we have calculated ab initio atomic partial charges for proteins of collagen and the brome mosaic virus (BMV) capsid. These proteins contain from 1000-3000 atoms and efficient and accurate ab initio quantum modeling methods have only become more recently available for …
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Ab initio calculations of mechanical, thermodynamic and electronic structure properties of mullite, Iota-alumina and boron carbide
… for each phase and relaxed using the Vienna ab initio simulation package (VASP) program. The model with the lowest total energy for a given x was chosen as the representative structure for that phase. Electronic structure and mechanical properties of mullite phases were studied via …
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An empirical potential for hydrogen bond energies determination of the orientation of anthracene molecules in the unit cell by means of a refractivity method: some ab initio calculations involving acetonitrile exchange reaction
… between the empirical potential and the ab initio results of 216 configurations of (H₂O)₂, (NH₃)₂ and NH₃•H₂O is 0.9 kcal/mol and 0.5 kcal/mol for 61 configurations of methanol dimers. Applications of the potential to water dimers, ammonia dimers, their mixed dimers, water oligomers and …
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Photoelectron Imaging of Iodide Centered Alkyl Halide Cluster Anions
… interaction. The results are compared with ab initio calculations as well as the electron scattering literature. The bulk of this dissertation discusses the role of the target molecule in cluster anion photodetachment. The insights developed from the I−·CH3X cluster anions are applied to …
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Lattice Dynamics in Temperature-driven and Photo-induced Phase Transitions
… anharmonicity without using first-principles calculations, for instance to obtain renormalized second- order and higher-order force-constants. Moreover, pump-probe experiments can now resolved femtosecond atomic dynamics by using an ultrafast laser pulse to excite materials out of equilibrium …
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Mechanisms of Methoxide Ion Substitution and Acid- Catalyzed Z/E Isomerization of N-Methoxyimines
… ∆S≠ = -17 eu for 1e and ∆S≠ = -9.9 eu for 2e. Ab initio calculations (HF/6-31+G*, MP2/6-31+G*//HF/6-31+G*, B3LYP/6- 31+G*//HF/6-31+G*, HF-SCIPCM/6-31+G*//HF/6-31+G*) were performed to define the reaction surface. These calculations demonstrate a relatively large barrier for nucleophilic attack …
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Sensitive and high-precision rovibrational spectroscopy of molecular ions relevant to astronomical and quantum chemistry
… spectroscopy of molecular ions has enabled new discoveries in astronomy and provided valuable benchmarks for ab initio calculations of molecular structure. Astronomers and theorists require accurate and precise laboratory measurements of rotational and rovibrational transition …
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Thermodynamic modelling as applied to the development of TRIP-Matrix-Composite materials: The Fe–Mg–Mn–Ti–Zr–O system
This thesis performed within the Collaborative Research Center 799 describes a development of the metal-ceramic thermodynamic databases as applied to the design of the TRIP-Matrix-Composite materials. A wide range of theoretical and experimental investigations have been carried out in the relevant …
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Sixteen valence-electron species containing boron: structural diversity abounds
… N, O, H₂] have been investigated via high level ab initio calculations. Both cyclic and acyclic connectivities have been examined for the singlet state. Chemical intuition suggests a ketene-like structure for each system, with the general form H₂XBY, where X = C or N and Y = F or O. The …
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Ab-initio simulation of novel solid electrolytes
… electrolytes in use today. I report results of ab-initio calculations on a related system of materials, Nai0 MP 2SI 2 (M = Ge, Si, Sn), which are predicted to have similar properties to LGPS as candidates for electrolytes in Na-ion batteries. I also derive methods to estimate the error …
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Astrochemical dynamics: Fundamental studies relevant to titan's atmosphere
… In the diacetylene dimer, it is shown, via laboratory studies combined with electronic structure calculations that the photodissociation of the dimer readily initiates atomic hydrogen (H) loss and atomic H transfer reactions forming two prototypes of resonantly stabilized free radicals, C8H3 …
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Hyper-Rayleigh scattering measurements of hyperpolarizabilities for tetrahedral molecules
First hyperpolarizabilities beta of carbon tetrachloride, carbon tetrafluoride, deuterated methane, and methane have been measured by hyper-Rayleigh scattering in gas and liquid phases. The gas-phase results for the coefficient beta xyz (atomic units) are 11.0 +/- 0.9 (CC14), 5.4 +/- 0.4 (CF4), 7.0 …
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Electronic Stucture of Elemental Boron
… to elucidate the properties of these phases, ab initio calculations have been performed to obtain the electronic structure and optical properties of the system from a fundamental quantum mechanical point of view. Also calculated are the Xray Absorption Near Edge Structure (XANES) spectra which …
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