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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 86 (1982), S. 1107-1111 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 79 (1975), S. 654-660 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 94 (1990), S. 7880-7888 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 5918-5929 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The perturbation theory for the total energies of the 1sσg and 2pσu states of H+2 is reformulated in a manner which avoids problems resulting from symmetrization. First a new set of localized wave functions are defined and calculated from polarization perturbation theory. After symmetrization of these wave functions, a generalized Heitler–London energy, which can be expanded to all orders, is obtained. In second order the result agrees with the Murrell–Shaw Musher–Amos expression. An expansion of the expectation value of the energy is also carried out and provides similar results. Many symmetry-adapted perturbation results are obtained simply and directly from the present localized wave-function approach. The present theory suggests a novel interpretation of the terms contributing to the total potential energy and helps to rearrange them to give improved results.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 1144-1150 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A simple model for van der Waals potentials presented earlier [J. Chem. Phys. 80, 3726 (1984)] has been extended to describe chemical bonds by including the exchange-dispersion term of Herring and Flicker. For H2, the 1Σ ground state potential is predicted in excellent agreement with the accurately known ab initio potential, the well depth being reproduced to within 0.6%. New two configuration self-consistent-field (SCF) calculations for the 1Σ and the 3Σ states of Li2 have made it possible to test the model for this system as well. Here the discrepancy is only 3% in the well depth for the 1Σ Li2 potential.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 7266-7277 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The Rayleigh–Schrödinger (polarization) perturbation theory without symmetrization is used to calculate the exchange energy of H+2 through the surface integral of Holstein–Herring. It is mathematically proven that the exchange energy series so obtained is exact in the same sense as Herring's result is exact. It is shown that the contributions to the leading term of the exchange energy series from all orders of polarized wave functions can be calculated exactly. Furthermore, it is explicitly demonstrated that the sum of these contributions converges to the exact value. The rate of convergence is relatively fast. With the first four orders of wave function, virtually 100% of the asymptotic exchange energy is recovered. With the present theory, terms other than the leading one can also be calculated systematically. This is demonstrated by the calculation of the first three terms of the exchange energy series from the first- and second-order wave functions.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 5465-5474 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The anisotropic potentials of He–N2, Ne–N2, and Ar–N2 are predicted using the Tang–Toennies potential model. This model damps the long-range ab initio dispersion terms individually using a universal damping function and adds to this a simple Born–Mayer repulsive term. The Born–Mayer parameters for the three systems were derived from SCF calculations. The dispersion coefficients were estimated from established combining rules using an effective multipole spectrum for the N2 molecule computed by Visser and Wormer from the time-dependent coupled Hartree–Fock approximation. The resulting potentials were used to predict the second interaction virial coefficients for each system, and they are found to be in excellent agreement with experiment. It is concluded that the spherical symmetric potentials are within 2%–3% of the true potentials. Some discrepancies with recent molecular beam experiments appear to be present, however, for the anisotropies especially in the case of He–N2. Finally, it is found that the law of corresponding states for anisotropic systems, which predicts that the reduced shapes of the potentials for a given geometrical configuration are identical, also holds for the highly anisotropic rare gas–N2 systems.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 3579-3579 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 377-388 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The surface integral method of Holstein and Herring is applied to the calculation of the exchange energy of the H2 molecule. This theory provides a means for calculating the exchange energy by taking into account the physical exchange of the two electrons with respect to the nuclei. Problems associated with symmetrization of the polarized wave functions which have encumbered previous attempts at developing a perturbation theory of the chemical bond are circumvented. Whereas the previous calculations using this method by Gor'kov and Pitaevski and Herring and Flicker were restricted to the asymptotic (R→∞) limit, in the present calculation we have used an extended formula to examine the validity also for the short range region down to R=0.5 a.u. In order to compare with the results of Heitler–London theory we have used the undisturbed zeroth order wave function of the H atoms in the calculations. An analytic expression is obtained for the exchange energy and the numerical results are found to be in good agreement with the exact calculations of Kolos and Wolnicwicz with an error of less than 20% for R≤8 a.u., where the zeroth order approximation is best justified. The agreement with the exact results is comparable to that of the original Heitler–London theory. The good agreement indicates that the basic assumption of the theory that electrons exchange places with respect to the nuclei is on a good physical basis and refutes previous textbook wisdom that the exchange energy cannot be given a simple physical interpretation.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of social welfare 6 (1997), S. 0 
    ISSN: 1468-2397
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Sociology
    Notes: In the last two decades, the conservative critique of the welfare state has been very strong. This study examines the claim of neoconservatives that there is a mass repudiation of the welfare state in the advanced industrial countries. Empirical opinion survey findings from Great Britain and the United States between 1960 and 1990 are examined. Contrary to the radical right rhetoric, there is popular support for social programs in both countries. Evidence also points to sizeable support for a mixed economy of welfare. Three explanations are put forward to account for enduring public support for social programs: the prevalence of social rights, support from the poor and middle class and the limitations of markets.
    Type of Medium: Electronic Resource
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