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An accurate ab initio quartic force field for ammoniaThe quartic force field of ammonia is computed using basis sets of spdf/spd and spdfg/spdf quality and an augmented coupled cluster method. After correcting for Fermi resonance, the computed fundamentals and nu 4 overtones agree on average to better than 3/cm with the experimental ones except for nu 2. The discrepancy for nu 2 is principally due to higher-order anharmonicity effects. The computed omega 1, omega 3, and omega 4 confirm the recent experimental determination by Lehmann and Coy (1988) but are associated with smaller error bars. The discrepancy between the computed and experimental omega 2 is far outside the expected error range, which is also attributed to higher-order anharmonicity effects not accounted for in the experimental determination. Spectroscopic constants are predicted for a number of symmetric and asymmetric top isotopomers of NH3.
Document ID
19930035836
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Martin, J. M. L.
(NASA Ames Research Center Moffett Field, CA, United States)
Lee, Timothy J.
(NASA Ames Research Center Moffett Field, CA, United States)
Taylor, Peter R.
(Eloret Inst. Palo Alto, CA, United States)
Date Acquired
August 15, 2013
Publication Date
December 1, 1992
Publication Information
Publication: Journal of Chemical Physics
Volume: 97
Issue: 11
ISSN: 0021-9606
Subject Category
Atomic And Molecular Physics
Accession Number
93A19833
Funding Number(s)
CONTRACT_GRANT: NCC2-371
Distribution Limits
Public
Copyright
Other

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