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Author Arapiraca, A. F. C. ♦ Mohallem, J. R.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ BENZENE ♦ BORN-OPPENHEIMER APPROXIMATION ♦ COMPUTER CALCULATIONS ♦ DIPOLE MOMENTS ♦ EXPERIMENTAL DATA ♦ METHANE
Abstract DFT-B3LYP post-Born-Oppenheimer (finite-nuclear-mass-correction (FNMC)) calculations of vibrationally averaged isotopic dipole moments of methane and benzene, which compare well with experimental values, are reported. For methane, in addition to the principal vibrational contribution to the molecular asymmetry, FNMC accounts for the surprisingly large Born-Oppenheimer error of about 34% to the dipole moments. This unexpected result is explained in terms of concurrent electronic and vibrational contributions. The calculated dipole moment of C{sub 6}H{sub 3}D{sub 3} is about twice as large as the measured dipole moment of C{sub 6}H{sub 5}D. Computational progress is advanced concerning applications to larger systems and the choice of appropriate basis sets. The simpler procedure of performing vibrational averaging on the Born-Oppenheimer level and then adding the FNMC contribution evaluated at the equilibrium distance is shown to be appropriate. Also, the basis set choice is made by heuristic analysis of the physical behavior of the systems, instead of by comparison with experiments.
ISSN 00219606
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-04-14
Publisher Place United States
Journal Journal of Chemical Physics
Volume Number 144
Issue Number 14


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