Methods for the calculation of Voh in OHO hydrogen bonds

✍ Scribed by Jeanne G.C.M. van Duijneveldt-van de Rijdt; Frans B. van Duijneveldt

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 978 KB
• Volume: 13
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.540130402

✦ Synopsis

Ab initio calculations are reported for dimerization-induced changes, Ak, in the harmonic force constant k of the H-bonded OH in water dimer. Two dimer geometries are considered. Ak is obtained by considering the perturbation of a given monomer OH potential by the interaction energy in the dimer in question. The interaction energy is partitioned to identify the role of the various contributions to Ak. The sensitivity of Ak to the choice of the one-electron basis set is studied by using five different basis sets, some of which have a set of bond functions in the H-O bond. At the correlated level, correction for basis set superposition error is found to be essential. A cornpaxison is made of the correlation contribution to Ak as given by the CEPA-I, MP2, MP3, and MP4 methods. Of these, MP2 gives exaggerated results. Nevertheless, for economical and reasonably accurate calculations on large systems the MP2 approach in the ESPB basis set is advocated. The most accurate calculations yield a shift Au&, of -121 cm-' for the uncoupled donor 0-H vibrational frequency in water dimer.