Article Abstract:
Ab initio molecular orbital calculations were used in studying the structures and relative stabilities of the cationic forms of the halogen dioxides. The geometries and the harmonic vibrational frequencies of all possible isomers were calculated at the QCISD/6-311+G(2d) level of theory for fluorine- and chlorine-containing compounds. The effective core-potential basis sets of Hay and Wadt, modified to include a set of diffuse functions and two sets of polarization functions, were employed for bromine- and iodine-containing compounds.
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Article Abstract:
Numerous theoretical and experimental experiments have been conducted to probe water in pores. A Monte Carlo simulation was conducted of water in a small pore to investigate the motions of individual molecules. The experiment would add to results of studies on water in pores, particularly pores in proteins and, especially, ion channels. Among other results, it was found that immobilized molecules are hardly reliant on density despite the fact that average energies and intermolecular distances exhibit appreciable dependence.
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Article Abstract:
The C-H...O hydrogen dimer pattern of the fragment O = C-C(=C)-H as occurring in 1,4-benzoquinone were studied by performing ab initio molecular orbital calculations. A statistical analysis of published crystal structures containing this dimer were combined with the computations. The optimal geometry obtained at the SCF + MP2 level of theory was very close to the mean geometry observed in crystals. All the dimer geometries observed in crystals were in the low-energy region of the potential energy surface.
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