Equilibrium inversion barrier of NH3 from extrapolated coupled-cluster pair energies
✍ Scribed by Wim Klopper; Claire C. M. Samson; György Tarczay; Attila G. Császár
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 141 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0192-8651
- DOI
- 10.1002/jcc.1088
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✦ Synopsis
Abstract
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 NH~3~. 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