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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 34 (1988), S. 279-288 
    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 pair correlation energies for some nl4f pairs of the ground state of the Yb atom are calculated for the first time. The partial wave (PW) increments to the second-order pair energies are generated using numerical first-order radial pair functions obtained as the solution of two-dimensional differential equations. The analysis of the PWs contributions shows the dominant role of the df, fg, and gh PWs for the 4d4f pair, of the pf and dg PWs for the 4p4f and 5p4f pairs, and of the sf and pg PWs for the 4s4f, 5s4f, and 6s4f pairs. A discussion of the similarities and differences of the structure of the correlation energy found in this paper with those calculated earlier for smaller atoms is given.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 27 (1985), S. 665-675 
    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: Second-order Rayleigh-Schrödinger Hartree-Fock perturbation theory is applied to evaluate the correlation energy for the 4f14 shell of Yb. The partial-wave (PW) increments to the pair energies, and the total correlation energy are calculated using first-order radial pair functions obtained as the solution of two-dimensional differential equations. These equations are solved using the Chalmers University version of the finite difference method. The total second-order correlation energy amounts to 0.89573 hartree. The results for the pair energies, which are close to the all-external pair energies, are compared with related CI values. It turns out that the correlation effects within the 4f shell of rare-earth systems are dominated by the all-external effects. The ff and gg PWS are dominant in the description of the correlation effects in the 4f shell and provide 80% of the total correlation energy. Next in importance are the dd, hh, and dg PWS which provide 12% of the total correlation energy.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Basic drug compounds ; Amino additives ; Cyanoalkyl columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of basic antidepressant and antipsychotic drugs on a cyanoalkyl-bonded silica column has been studied to determine the effects on peak retention, symmetry, efficiency, and resolution of six different amine mobile-phase additives. The amines—ammonia,n-butylamine, triethylamine,N,N-diisopropylethylamine,N,N-dimethylbutylamine andN,N-dimethyloctylamine—were, except forN,N-diisopropylethylamine, chosen because of their widespread use for improvement of peak symmetry in chromatographic methods;N,N-diisopropylethylamine was included as an example of a sterically hindered amine to see if the stereochemistry around the nitrogen atom is an important consideration in the selection of an additive. This study shows that a gain in symmetry and efficiency is accompanied by loss of resolution. The results obtained also indicate that one type of amine additive should be used when symmetry and efficiency are most important and another when resolution is paramount.
    Type of Medium: Electronic Resource
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