Ss. Xantheas et Th. Dunning, THE STRUCTURE OF THE WATER TRIMER FROM ABINITIO CALCULATIONS, The Journal of chemical physics, 98(10), 1993, pp. 8037-8040
The first fully optimized structure of the water trimer at the MP2 lev
el of theory is reported. It corresponds to a cyclic chiral structure
in which all O-O separations are equal to 2.80 angstrom, the O(alpha)H
... O(beta) hydrogen bonds are nonlinear, and two of the terminal hyd
rogens lie on one side of the O-O-O plane and the third lies on the ot
her. This structure is in qualitative agreement with that reported rec
ently by Pugliano and Saykally [Science 257, 1937 (1992)]. However, th
e calculations predict the O-O separations to be substantially shorter
than those used to fit the far-infrared vibration-rotation-tunneling
spectrum. Nonetheless, the computed structure reproduces the measured
rotational constants of (D2O)3 ; the errors are < 1% for A and B and 6
% for C An energy analysis yields a three-body term of 2.3 kcal/mol (a
pproximately 15% of D(e) with respect to three isolated water molecule
s).