Characterization of the bifurcated structure of the water dimer

The bifurcated structure of the water dimer has been the subject of considerable uncertainty with respect to its vibrational characterization. We have considered this question at the self-consistent-field (SCF) level of theory using finite basis sets that allow a close approach to the Hartree–Fock limit. As one approaches the Hartree–Fock limit, the bifurcated structure is predicted to be a true transition state, with one imaginary vibrational frequency, ω12(B2)∼200i cm−1.