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Torsional eigenvalues of the water trimer on several ab initio potential surfaces
Author(s) -
Guiang Chona S.,
Wyatt Robert E.
Publication year - 1998
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1998)68:4<233::aid-qua2>3.0.co;2-w
Subject(s) - counterpoise , trimer , ab initio , chemistry , ab initio quantum chemistry methods , potential energy surface , potential energy , isotopomers , eigenvalues and eigenvectors , triatomic molecule , computational chemistry , molecular physics , atomic physics , physics , basis set , quantum mechanics , density functional theory , molecule , dimer , organic chemistry
Abstract Eigenvalues corresponding to the three torsional degrees of freedom were calculated for the water trimer and its deuterated isotopomer in four sets of calculations involving different potential energy surfaces. The four potential surfaces were developed in this work by reparametrization of the CKL function against four sets of ab initio energies calculated with and without counterpoise correction. Transition frequencies corresponding to the low‐frequency torsional motions of the trimer were calculated and then compared with those found from experiment to assess the accuracy of each potential energy surface. Although reparametrization of the CKL function to a set of counterpoise‐corrected energies yielded transition energies that are in qualitative agreement with those from experiment, reparametrization to another set of counterpoise‐corrected energies resulted in highly inaccurate values of the transition energy. As a consequence, our results demonstrate that caution must be exercised in the implementation of the counterpoise method as it does not always lead to more accurate ab initio calculations. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 68: 233–252, 1998