We present an analysis of the structural, energetic and spectral
features associated with the different hydrogen bonded networks found in
the first few acetylene-water clusters AW(n) (n = 1-4) from first
principles calculations. Contrary to the predictions of an empirical
interaction potential, acetylene is incorporated into a hydrogen bonded
ring when it clusters with two or three water molecules. This structural
pattern changes for n = 4 with the formation of a water tetramer
interacting with acetylene. This structural transition from n = 3 to 4
is spectroscopically manifested by a qualitative change in the
appearance of the infrared spectra of the corresponding global minima.
(C) 2001 Published by Elsevier Science B.V
