Premium
Equilibrium inversion barrier of NH 3 from extrapolated coupled‐cluster pair energies
Author(s) -
Klopper Wim,
Samson Claire C. M.,
Tarczay György,
Császár Attila G.
Publication year - 2001
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.1088
Subject(s) - extrapolation , coupled cluster , diagonal , chemistry , basis set , atomic physics , physics , cluster (spacecraft) , quantum mechanics , molecule , mathematics , mathematical analysis , geometry , computer science , programming language
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