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  • 1
    Electronic Resource
    Electronic Resource
    Ab initio potentials and pressure second virial coefficients for CH4–H2O and CH4–H2S (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 7808-7812 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ab initio Hartree–Fock (HF) and second-order many-body perturbation theory (E2) were used to generate data for pair potentials of the mixtures CH4–H2S and CH4–H2O. The points were fit with site–site functions consisting of terms for interactions of the following types: exponential repulsion and R−6 and electrostatic attraction. The basis sets of Gaussian functions were developed by systematically adding polarization functions to maximize the zeroth-order dipole polarizability; the counterpoise method was used to correct basis set superposition error. The best well depths calculated for CH4–H2S and CH4–H2O were −0.0227 and −0.0215 eV, respectively (with no experimental results available for comparison). The potentials were evaluated by examining errors in the dipole polarizabilities and pressure second virial coefficients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459362
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  • 2
    Electronic Resource
    Electronic Resource
    Coupled Hartree–Fock dipole polarizabilities of the smaller n-alkanes CnH2n+2(n≤7) (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 7264-7267 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have calculated the dipole polarizabilities of the "chain'' alkanes CnH2n+2 (n ≤7) using the coupled Hartree–Fock method. Our average values are 97%–98% of gas phase experimental values. For the larger alkanes, each CH2 unit adds 12.3 a.u. to the average value (within 2%). The anisotropic polarizability also agrees well with gas phase experimental values, but it continues to increase with the length of the chain. We have also obtained dipole moments for the odd alkanes−propane, pentane, and heptane. For propane, there is a gas phase experimental value with which we agree quite well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459449
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  • 3
    Electronic Resource
    Electronic Resource
    Erratum: Ab initio potentials for (H2S)2, including studies of effects from third-order many-body perturbation theory and three-body nonadditivity [J. Chem. Phys. 92, 3605 (1990)] (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 6338-6338 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458610
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  • 4
    Electronic Resource
    Electronic Resource
    Obtaining accurate pressure second virial coefficients for methane from an ab initio pair potential (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 9106-9114 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The pressure second virial coefficients, including fourth-order many-body effects, have been calculated for methane and are found to agree with the experiment on the average, to 2.8% over the temperature range 110–623 K using the basis set of Sadlej. This is a major improvement over the usual 30%–40% accuracy of ab initio potentials and also has been attained by us for H2O. Monte Carlo simulations have also been performed with the potential and a C–C radial distribution function and the internal energy is obtained. The latter (−0.0757 eV/molecule) is in good agreement with experiment (−0.0738 eV/molecule).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461189
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  • 5
    Electronic Resource
    Electronic Resource
    Ab initio potentials for (H2S)2, including studies of effects from third-order many-body perturbation theory and three-body nonadditivity (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 3605-3609 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ab initio Hartree–Fock (HF) and many-body perturbation theory through second (E2) and third order (E3) were used to generate pair potentials for (H2S)2. Several basis sets were developed by optimizing polarization functions with the zeroth-order dipole or quadrupole polarizabilities. Approximately 30 ab initio points (fully counterpoised HF+E2) in each of two larger basis sets were fit with site–site potentials. Intermediate potentials for fewer points indicate that only about 30 points are a sufficient data base to predict energies in the vicinity of the well with an accuracy of about 10%. The best ab initio well depth produced (−0.0693 eV) lies at 94% of the only published experimental value (−0.074±0.013 eV), although arguments are presented which indicate that the true (H2S)2 minimum may lie below −0.08 eV. The role of E3 and nonadditive effects has also been explored, but they were found not to account for the major part of the remaining discrepancy between our best number and experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457868
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  • 6
    Electronic Resource
    Electronic Resource
    Crucial role of electron correlation in both the upper and lower states in optical transitions (1974)
    Springer
    Theoretical chemistry accounts 34 (1974), S. 183-187 
    Details
    ISSN: 1432-2234
    Keywords: Oscillator strength ; Electron correlation ; Optical transitions ; Non-closed shell theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It is demonstrated that the specifically non-closed shell type correlation effects of the Non-Closed Shell Many-Electron (NCMET) Electronic Structure theory of Sinanoğlu, in both states of an allowed transition affect the electric dipole oscillator strengths by large factors. Detailed Hartree-Fock and NCMET calculations on the Cl III 3s 23p 3(4 S 0)→3s3p 4(4 P) display the effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00578415
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  • 7
    Electronic Resource
    Electronic Resource
    Configuration interaction methods for improving unrestricted Hartree-Fock spin densities (1979)
    Springer
    Theoretical chemistry accounts 52 (1979), S. 329-340 
    Details
    ISSN: 1432-2234
    Keywords: UHF spin densities ; CI method for improving ∼ ; Spin densities, UHF ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Limited Configuration Interaction wave functions based on Unrestricted Hartree-Fock natural orbitals are found to be easy to compute and to give much more satisfactory spin densities than are provided by techniques currently in use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00549092
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  • 8
    Electronic Resource
    Electronic Resource
    Soil and plant water stress in an Appalachian oak forest in relation to topography and stand age (1984)
    Springer
    Plant and soil 80 (1984), S. 171-179 
    Details
    ISSN: 1573-5036
    Keywords: Forest site quality index ; Plant moisture stress ; Predawn plant water potential ; Soil water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A Forest Site Quality Index (FSQI) formulated to predict site quality in Ridge and Valley terrain based on the topographic parameters of aspect, slope inclination and slope position was used to verify moisture gradients along the southeast face of Potts Mountain in Craig County, Virginia. A gradient of site quality index values representing xeric to mesic sites was established in both recently clearcut and adjacent uncut second-growth forest stands. Soil moisture content was determined gravimetrically at ten day intervals from May to October, 1981. Plant moisture stress measurements were taken in conjunction with soil moisture sampling using the pressure chamber technique on three dominant hardwood tree species. For both clearcut and uncut forest stands, a general gradient of increasing soil moisture availability with increasing FSQI was evident, although differences were not large between index values of 8 and 11 in either stand type. Soil water potential and predawn plant water potential exhibited a strong seasonal trend, their direct relationship suggesting that available soil water is probably the critical factor controlling base P levels. Growth limiting stress levels began in late July and continued for the remainder of the growing season.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02161173
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  • 9
    Electronic Resource
    Electronic Resource
    Time dependence, complex scaling, and the calculation of resonances in many-electron systems (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 457-513 
    Details
    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: The theory of this paper deals with certain aspects of the formal properties of atomic and molecular highly excited nonstationary states and the problem of calculating their wave functions, energies, and widths. The conceptual framework is a decay theory based on the consistent definition and calculation of the t = 0 localized state, |Ψ. Given this framework, the following topics are treated: (a) The variational calculation of Ψ0 and E0 using a previously published theory that generalized the projection operator approach to many-electron systems. (b) The exact definition of the resonance energy. (c) The possibility of bound states in the continuum. (d) The relation of Ψ0 to the resonance (Gamow) function Ψ and of the Hamiltonian to the rotated Hamiltonian H(θ) based on the notion of perturbation of boundary conditions in the asymptotic region. (e) The variational calculation of real and complex energies employing matrix elements of H and H2 with square-integrable and resonance functions. (f) The mathematical structure of the time evolution of |Ψ0〉 and the possibility of observing nonexponential decays in certain autoionizing states that are very close to the ionization threshold. (g) A many-body theory of atomic and molecular resonances that employs the coordinate rotation method.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140411
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  • 10
    Electronic Resource
    Electronic Resource
    Fine and hyperfine structure of the two lowest bound states of Be- and their first two ionization thresholds (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 467-481 
    Details
    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: The two lowest bound excited states of the Be- ion, 1s2 2s2p2 4P and 1s2 2p3 4S0, and their respective thresholds, Be 1s2 2s2p 3P0 and Be 1s2 2p2 3P, and the thresholds of these, Be+ 1s2 2s and Be+ 1s2 2p, have been examined using many-body methods. Here, we present the electron affinities (EAs) or ionization potentials, fine and hyperfine structure, and the electric dipole transition probabilities associated with these states and compare them with existing theory and experiment when available. Based on our new EA, a suggestion is made as to why no negative ion transition has yet been seen in the laboratory.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260843
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