Rearrangements and tunneling splittings of protonated water dimer

Stationary points and rearrangement mechanisms are characterized for protonated water dimer with a variety of basis sets and both Moller-Plesset and density functional theory to describe electron correlation. The results are consistent at each level of theory and suggest that this molecule will exhibit interesting tunneling splitting patterns which should be resolvable experimentally. (C) 1999 American Institute of Physics. [S0021-9606(99)02819-6].