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Ab initio molecular orbital study of OH − (H 2 O) n in the gas phase
Author(s) -
Masamura Masao
Publication year - 2000
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 - 10.1002/1096-987x(20010115)22:1<31::aid-jcc4>3.0.co;2-e
Subject(s) - ab initio , gas phase , conformational isomerism , molecule , chemistry , ab initio quantum chemistry methods , physics , crystallography , atomic physics , computational chemistry , thermodynamics , quantum mechanics
The purpose of this article is to show that (1) the OH − ion binds strongly to up to five water molecules in the gas phase; (2) relative stability of several conformers of OH − (H 2 O) n ( n =4 and 5); (3) how we reproduce \documentclass{article}\pagestyle{empty}\begin{document}$\Delta H_{n-1,n}^{0}$\end{document} of OH − (H 2 O) n ; and (4) the shift of the OH harmonic frequencies of optimal geometries of OH − (H 2 O) n ( n =0–5). For this purpose, full geometry optimizations were carried out using the MP2/aug‐cc‐pVDZ method for OH − (H 2 O) n ( n =0,1,2,3,4,5,6) and H 2 O. Also, MP4/aug‐cc‐pVDZ// MP2/aug‐cc‐pVDZ, CCSD(T)/aug‐cc‐pVDZ//MP2/aug‐cc‐pVDZ and MP2/aug‐cc‐pV x Z//MP2/aug‐cc‐pVDZ ( x =T,Q,5) calculations were performed. For n =4, the stability of C 4 symmetry is equal to that of “3‐1(2),” and “3‐1(1)” is considerably unstable. For n =5, “4‐1(2)” is more stable that C 5 symmetry and “4‐1(1)” by 2 kcal/mol. The maximum number of water molecules that can directly interact with the O of OH − is 5 in the gas phase. Based on the shift of the calculated OH harmonic frequencies, we discuss the possible identification of the isomers in the vibrational spectroscopy. © 2000 John Wiley & Sons, Inc. J Comput Chem 22: 31–37, 2001