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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 8070-8082 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: For the electronic ground state of CO+2 the three-dimensional potential energy, electric dipole, and transition moment functions have been calculated from highly correlated multireference configuration interaction electronic wave functions. Along the antisymmetric stretching displacements the shape of the potential energy functions is found to be very sensitive to the electron correlation effect. Using a modified theoretical potential energy function rovibronic energy levels have been calculated variationally by the method of Carter and Handy. In this approach, anharmonicity, rotation–vibration, electronic angular momenta, and electron spin coupling effects have been accounted for. The vibronic band origins agree to within about 10 to 20 cm−1 with the available experimental data, and the rotational levels agree to within 0.01 cm−1 for low J values. Additional vibrational band origins have been predicted for energies up to 3200 cm−1. The anomalously low frequency of the antisymmetric stretching mode and its inverse anharmonicity in the X 2Πg state of CO+2 have been reproduced with the potential energy functions for the adiabatic states. Previously, it has been assumed that this effect is due to the vibronic coupling. The molecular parameters of one-dimensional effective Hamiltonians obtained from fits of the spectral data are compared with those derived from the theoretical potential.
    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 99 (1993), S. 897-900 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using variational rotational–vibrational wave functions and ab initio electric dipole moment functions, rotational–vibrational line strengths and integrated vibrational band intensities of water vapor have been calculated. The theoretical line strengths are in excellent agreement with existing experimental data.
    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 83 (1985), S. 4661-4667 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Potential energy and dipole moment functions for the ground states of SH, SH+, and SH− have been calculated from highly correlated electronic wave functions. The electric dipole moments in the vibrational ground states of 32SH, 32SH+, and 32SH− are calculated to be 0.74, 1.29, and 0.27 D, and the rotationless rates of spontaneous emission A10 to be 1, 52, and 75 s−1, respectively. The predicted transition probabilities between the low lying vibrational states of the electronic ground state of SH and SD are among the smallest so far known for dipole allowed rotation-vibration transitions. The calculated A–X transition probabilities in SH confirm recent indirect determinations of the radiative lifetimes and absorption oscillator strengths in the predissociating v'=0 level of the A state. The 4Σ− state is calculated to intersect the A 2Σ+ state at R=3.1 a.u., between the classical turning points of v'=0 and 1 in the A state.
    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 83 (1985), S. 5784-5791 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In order to calculate frequency dependent polarizabilities, time dependent perturbation theory for MC-SCF wave functions has been used and a significant part of the correlation contribution is accounted for. Explicit formulas for the coefficients of the system of linear equations to be solved have been given. The results reported for α(ω) of He, H2, Ne, HF, H2O, NH3, and CH4 show that in the case of the two electron systems excellent results can be obtained and that in the case of the ten electron systems with 45-configuration wave functions about 80% of the correlation contribution for ω=0 have been included. The absolute accuracy for the latter case is in the range of 4% to 9.5%. For large ω values the experimental polarizability increases slightly more than the calculated values.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 11 (1968), S. 296-306 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Elektronenstruktur eines Nickel(II)-Acetylen-Komplexes wird nach dem Verfahren von Wolfsberg-Helmholtz berechnet, um die katalytische Wirkung von Ni2+-Komplexen bei der Tetramerisierung von Acetylen zu klären. Die Rechnungen zeigen, daß diese Wirkung wahrscheinlich auf dem teilweisen Übergang der ungepaarten Elektronen des Nickelions auf zwei Acetylen-Liganden beruht. Dieser Übergang findet statt, wenn diese Liganden eine bestimmte geometrische Lage einnehmen.
    Abstract: Résumé La structure électronique d'un complexe de nickel-(II)-acétylène est calculée à l'aide de la méthode Wolfsberg-Helmholtz en vue d'expliquer l'effet catalytique de complexes de Ni2+ dans la tétramerisation d'acétylène. D'après les calculs il semble que l'effet arrive d'une transition partielle des électrons non appariés aux ligands d'acétylène. La transition apparaît quand ces ligands sont dans une position geometrique déterminée.
    Notes: Abstract The electronic structure of a nickel(II)-acetylene complex is calculated according to the Wolfsberg-Helmholtz procedure in order to explain the catalytic action of nickel(II)-complexes in the tetramerization of acetylene. The calculations show that this action very likely arises from the partial transfer of the unpaired electrons of the nickel ion to two acetylene ligands. This transfer occurs when the appropriate ligands assume a specific geometrical position.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 30 (1973), S. 127-128 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 6 (1966), S. 453-454 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 23 (1971), S. 155-174 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird ein auf der Störungsrechnung basierendes ab initio Verfahren skizziert. Die nullte NÄherung ist ein System von Elektronen in einem Kasten bestimmter Grö\e und ohne Wechselwirkung. Die Störungsrechnung wird mittels der Brückner-Goldstone-Reihe durchgeführt, wobei noch die Glieder dritter Ordnung miteinbezogen werden.
    Notes: Abstract The extent of the computational work connected with the usual SCF-LCAO-procedure (i) increases enormously with the size of the molecule and (ii) has to be completely redone upon every change of the positions of the nuclei. Starting from this fact it is suggested to work with a procedure which can be based on the standard set of free electron functions. A number of electrons without interaction, enclosed in a box with constant potential, is regarded as an unperturbed system and the perturbation is the potential of the nuclei as well as the electron interaction. In order to make actual calculations possible it is necessary to perform the transition to a system which consists of a large number of molecules under consideration forming a lattice with each other. One can then use the formalism of the Brückner-Goldstone series, this procedure now being roughly independent of the number of electrons of the single molecule. The expressions for the graphs up to the third order are given.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 10 (1968), S. 465-466 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 19 (1970), S. 107-108 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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