Structures, energetics, and spectroscopic fingerprints of water clusters n = 2-24

Abstract

This chapter discusses the structures, energetics, and vibrational spectra of the first few (n ≤ 24) water clusters obtained from high-level electronic structure calculations. The results are discussed in the perspective of being used to parameterize/assess the accuracy of classical and quantum force fields for water. To this end, a general introduction with the classification of those force fields is presented. Several low-lying families of minima for the medium cluster sizes are considered. The transition from the “all surface” to the “fully coordinated” cluster structures occurring at n = 17 and its spectroscopic signature is presented. The various families of minima for n = 20 are discussed together with the low-energy networks of the pentagonal dodecahedron (H2O)20 water cage. Finally, the low-energy networks of the tetrakaidecahedron (T-cage) (H2O)24 cluster are shown and their significance in the construction of periodic lattices of structure I (sI) of the hydrate lattices is discussed.