M. Kreissler et al., AB-INITIO STUDY OF THE STRUCTURE, COOPERATIVITY AND VIBRATIONAL PROPERTIES OF THE H2O(HCL)(2) HYDROGEN-BONDED COMPLEX, Journal of molecular structure. Theochem, 452, 1998, pp. 55-66
Ab initio self consistent field (SCF) and second order Moller-Plesset
perturbation theory (MP2) calculations have been performed on order to
investigate the structure, energetics and spectroscopic properties of
H2O:(HCl)(2). Two minima have been located on the energy hypersurface
: a cyclic structure without any symmetry element and a bifurcated one
with a C-2v symmetry. In this latter complex the two hydrogen bonds a
re equivalent, whereas in the former there are two relatively strong H
-bonds and a weaker one between the terminal sub-units. The calculated
energy difference between these two conformers is about 1.0 kcal mol(
-1) in favor of the cyclic complex and is very method dependant. The r
elative stability of the two conformers is mostly governed three-body
forces which are attractives in the case of the cyclic structure, and
repulsives in the bifurcated complex. The calculated frequency shifts
within the cyclic trimer agree with the observed shifts in the argon m
atrix. (C) 1998 Elsevier Science B.V. All rights reserved.