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  • Hydrogen bonding  (3)
  • Inorganic, Organic and Physical Chemistry  (2)
  • 1
    Electronic Resource
    Electronic Resource
    A quantum chemical study of the hydrogen bonding in the CO2⋯HF and N2O⋯HF complexes (1989)
    Springer
    Theoretical chemistry accounts 76 (1989), S. 173-185 
    Details
    ISSN: 1432-2234
    Keywords: Hydrogen bonding ; CO2-HF complex ; N2O-HF complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Quantum chemical ab initio calculations have been performed for the complex CO2⋯HF and N2O⋯HF. The interaction energies were computed through fourth order MBPT and were corrected for basis set superposition errors. Extended polarized basis sets were used which are constructed to give accurate values for electric moments and polarizabilities. The complex NNO⋯HF was found to be bent, while OCO⋯HF is linear, in agreement with experiment. The MBPT calculations give evidence for a second linear isomeric structure FH⋯NNO, a possibility which has also been suggested by recent experimental data. The computed binding energies are: 2.5 kcal/mol for OCO⋯HF, 2.4 kcal/mol for NNO⋯HF, and 3.0 kcal/mol for FH⋯NNO. At the SCF level, the FH⋯NNO complex is less stable than NNO⋯HF, but correlation has a large effect on the geometry and energetics of the latter complex. The NNO⋯HF complex seems to be a system where the positive intramolecular correlation correction prevails over the negative intermolecular component.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00527471
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  • 2
    Electronic Resource
    Electronic Resource
    SCF-CI studies of the equilibrium structure and the proton transfer barrier H3O 2 − (1976)
    Springer
    Theoretical chemistry accounts 42 (1976), S. 77-82 
    Details
    ISSN: 1432-2234
    Keywords: Configuration interaction ; Hydrogen bonding ; Ion hydration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Large-scale configuration interaction (CI) calculations have been performed in order to study the effect of the correlation energy on the equilibrium geometrical structure, the stability, and on the energy barrier of the proton transfer reaction in the hydrogen bonded system HO− · HOH. An extended Gaussian basis set including polarization functions on each nuclear centre has been employed to approximate the molecular Orbitals. All possible single and double replacements resulting from a single determinant Hartree-Fock reference state have been taken into account in the CI wavefunction. Compared to the SCF results the equilibrium oxygen/oxygen distance has been obtained from the CI calculations to be smaller by about 0.08 Å and the correlation energy has been found to stabilize the composed system by 3.6 kcal/mole. An almost symmetric equilibrium structure with the hydrogen bonding H-atom midway between the two oxygen centres has been obtained in the CI treatment, whereas SCF calculations yield an asymmetric geometrical configuration with a small energy barrier of 1.4 kcal/mole for the proton transfer process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00548292
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  • 3
    Electronic Resource
    Electronic Resource
    SCF-CI studies of correlation effects on hydrogen bonding and ion hydration (1975)
    Springer
    Theoretical chemistry accounts 36 (1975), S. 249-274 
    Details
    ISSN: 1432-2234
    Keywords: Configuration interaction ; Hydrogen bonding ; Ion hydration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Previous single-determinant Hartree-Fock studies on the equilibrium structures and stabilities of H2 O, H3 O+ as well as of the monohydrated ionic systems Li+ · H2O, F− · H2O and the hydrogen bonded water dimer, H2 O · HOH, are extended by large scale configuration interaction calculations including all the possible single and double excitations arising from the canonical set of Hartree-Fock molecular orbitals. The correlation energy effects on the equilibrium geometrical parameters of the systems under consideration are found to be quite small. The contributions of the correlation energy to the total binding energies of the weakly interacting composed systems are obtained to be of the order of 1 kcal/mole, leading to a considerable increase of the hydrogen bond strength in F− · H2O and H2O · HOH and to a small decrease of the binding energy in Li+ · H2 O. The observed strengthening of the hydrogen bonding interaction due to correlation is shown to be partly compensated by the change in the vibrational zero-point energy of the composed systems compared to the non-interacting subsystems. Approximate force constants corresponding to the intersystem vibrations in Li+ · H2O, F− · H2 O, and H2O · HOH are deduced from the calculated potential curve data on the SCF and the CI level of accuracy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00549690
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  • 4
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    A Further Study of the Products of Sc and Dioxygen Reactions (1999)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: The products of the reaction of Sc and dioxygen have been reinvestigated. By adding the electron-trapping molecule CC14, additional information about the IR spectra has been obtained, as well as the observation of new bands. New ab initio calculations are also performed on possible products of the Sc plus O2 reaction. The previously observed band at 722.5 per cm is assigned as the b2 mode of ScO2(-). Bands arising from ScO(+), Sc(O2)(+), and(O2)ScO are also assigned. We are still unable to assign any bands to OScO. The problems associated with the computational study of ScO2 are discussed.
    Keywords: Inorganic, Organic and Physical Chemistry
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    NASA TECHNICAL REPORTS
  • 5
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    The Ozonide Anion: A Theoretical Study (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Complete active space self-consistent field (CASSCF) and CASSCF second order perturbation theory (CASPT2) methods have been used for the geometry optimization and calculation of harmonic and fundamental frequencies of the ozonide ion O3(-) and the ozonide lithium complex Li(+)O3(-). For O3(-) harmonic frequencies have also been obtained using the coupled-cluster method, CCSD(T). Infrared intensities are computed from dipole moment derivatives at the CASSCF level. The predicted equilibrium geometry for O3(-) is: Roo = 1.361 Angstroms and angle ooo = 115.4 degrees, and the fundamental frequencies are: nu(sub 1) = 989 per centimeter, nu(sub 2) 556 per centimeter, nu(sub 3) = 870 per centimeter (experimental values are: Roo =1.36 plus or minus 0.02 Angstroms, angle (ooo) = 111.8 plus or minus 2.0 degrees, nu(sub 1) = 975(50) per centimeter, nu(sub 2) = 550(50) per centimeter, nu(sub 3) = 880(50) per centimeter). Corresponding data for the lithium ozonide complex have also been obtained. The presented data contradict the previous interpretation of the IR and Raman spectrum obtained after deposition of ozone in N2, argon, or neon matrices with atomic beams of alkali metals. The presence of the lithium cation raises the asymmetric stretch frequency to about 940 per centimeter, which is contradictory to assumptions made in the assignments of the matrix spectra. Calculations made in a dielectric medium strongly suggest that the effect of the matrix on the IR spectrum is small for O3(-) itself. The dissociation and atomization energies of O3(-) are found to be in agreement with experiment.
    Keywords: Inorganic, Organic and Physical Chemistry
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    NASA TECHNICAL REPORTS
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