AB-INITIO STUDY OF THE ALX(3)CENTER-DOT-CENTER-DOT-CENTER-DOT-2H(2)O (X=F,CL) AND ALF3-CENTER-DOT-CENTER-DOT-CENTER-DOT-3H(2)O COMPLEXES

The structures, binding energies, and harmonic vibrational frequencies of AlX(3) ... 2H(2)O (X = F,Cl) complexes have been explored for the first time at the HF, DFT, and MP2 levels using the 6-31G, 6-31+G*, a nd the 6-311G* basis sets. The optimizations were performed without s ymmetry restrictions or other structural limitations. All complexes in vestigated were found to be energetically stable, regardless of the co mputational method used. The calculations showed that the DFT(B3LYP)/6 -31+G method is suitable for the prediction of both binding energies and vibrational frequencies for these types of complexes. This makes p ossible qualitatively accurate calculations at a relatively low comput ational expense of even larger, comparable complexes. The AlF3 ... 3H( 2)O complex was therefore investigated only at this level, yielding th e basis for the molecular interpretation of the first steps of the mac roscopically investigated hydration process of AlF3. A comparison of t he binding energies of complexes containing an increasing number of wa ter molecules has been performed. Furthermore, the vibrational frequen cies of all complexes have been predicted.