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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 11715-11721 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 6387-6391 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The energetics of the Cl2/MgO(001) interface were investigated using the ab initio periodic Hartree–Fock (PHF) method and local density functional correlation corrections to PHF theory, as implemented in the program CRYSTAL92. Estimates of the correlation corrected PHF energies are made by post-SCF evaluations of three gradient corrected functionals. The correlation energy is calculated from the fully converged ground state PHF charge density and added to the PHF total energy. This is the first study of interfacial energetics using the correlation corrected PHF theory. PHF and correlation corrected molecule/surface binding energies are reported for seven orientations of the adsorbate with respect to the surface plane. Three of the configurations align the intramolecular axes along the surface normal and the remaining geometries arrange the molecules heat-to-tail, parallel to the surface plane. The most favorable interaction occurs when chlorine approaches a surface oxygen along the normal direction. This site preference is consistent with a classical electrostatic description of the physisorption process. The binding energy increases with decreasing surface coverage. At the most dilute coverage studied (1:8) the PHF binding energy was 4.1 kcal/mol and the correlation corrected binding energies ranged from 9.2 to 10.3 kcal/mol. All three functionals tended to increase the molecule/surface attractions, shorten the molecule/surface equilibrium distance, increase the curvature of the molecule/surface potential energy surface near equilibrium, and reduce the molecule/molecule repulsions.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 6010-6017 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The properties of the Cl2/MgO (001) interface were investigated using the ab initio periodic Hartree–Fock LCAO method. The calculations treated a system that was periodic in two dimensions with the adsorbate aligned perpendicular to a three-layer slab of MgO (001). The total energy was calculated as the periodic net of Cl2 molecules approached either an oxygen or magnesium site on the surface. The finite thickness of the slab was set such that the interlayer atoms resembled those found in the bulk. The basis set for the solid has an optimized split valence form with 8–61G on Mg and 8–51G on O. The binding energy is reported as a function of Cl2 surface coverage, with a 6–21G* basis set on Cl, in the range from 1:1 to 1:8. At the most dilute coverage (1:8), the Cl2 molecule is bound over an oxygen with a binding energy of 4.1 kcal/mol. The energetics of Cl2 approaching a magnesium show a purely repulsive interaction at all coverages. The interfacial properties are probed with calculations of the band structure, total and projected density of states, density deformation maps, Mulliken analyses, and electrostatic potential maps. The charge density and density deformation maps indicate that the binding of the adsorbate involves very little charge transfer (only ∼0.03 ||e||) between the surface and the molecule. The calculated electrostatic potential and the electric field maps reveal that the interaction is dominated by the electrostatic interaction between the molecule and the surface. A simple electrostatic description of the attractive forces in the binding energy can account for the preference of the adsorbate to bind over oxygen. The total and projected density of states indicate that the higher energy valence states in the slab are dominated by contributions from the 2s and 2p orbitals centered on the oxygens. These states overlap and mix with the states resulting from the 3s and 3p orbitals of the Cl2 net. This mixing occurs to a much smaller extent between chlorine and magnesium orbitals.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 7295-7303 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 809-820 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silica sodalite is an ideal model system to establish base-line computer requirements of ab initio periodic Hartree-Fock (PHF) calculations of zeolites. In this article, we investigate the effect of various basis sets on the structural and electronic properties of bulk silica sodalite. We also study the interaction of He, Ne, and Ar with the sodalite cage. Our work shows that basis-set superposition errors (BSSE) in calculations using STO-3G and 6-21G(*) basis sets are as large as the interaction energies, leading to poor confidence in the results. To cure this problem, we present high-quality basis sets for Si, O. He, Ne, and Ar, optimized for use with PHF methods, and demonstrate that the new basis set greatly reduces BSSE. The theoretical barriers for transfer of the rare gases between sodalite cages are 5.6, 13.2, and 62.1 kcal/mol for He, Ne, and Ar. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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