Equilibrium inversion barrier of NH3 from extrapolated coupled-cluster pair energies

The basis‐set convergence of singlet and triplet pair energies of coupled‐cluster theory including single and double excitations is accelerated by means of extrapolations based on the distinct convergence behaviors of these pairs. The new extrapolation procedure predicts a nonrelativistic Born–Oppen...

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Bibliographic Details
Published in:Journal of computational chemistry 2001-10, Vol.22 (13), p.1306-1314
Main Authors: Klopper, Wim, Samson, Claire C. M., Tarczay, György, Császár, Attila G.
Format: Article
Language:English
Subjects:
ammonia
basis-set convergence
coupled-cluster theory
inversion barrier
pair energies
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Summary:The basis‐set convergence of singlet and triplet pair energies of coupled‐cluster theory including single and double excitations is accelerated by means of extrapolations based on the distinct convergence behaviors of these pairs. The new extrapolation procedure predicts a nonrelativistic Born–Oppenheimer inversion barrier of 1767±12 cm−1 for NH3. An effective one‐dimensional, vibrationally averaged barrier of 2021±20 cm−1 is obtained when relativistic effects (+20 cm−1), Born–Oppenheimer diagonal corrections (−10 cm−1), and zero‐point vibrations (+244 cm−1) are accounted for. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1306–1314, 2001
ISSN:0192-8651
1096-987X
DOI:10.1002/jcc.1088