NONADIABATIC MOLECULAR THEORY AND ITS APPLICATION - II - WATER MOLECULE

We introduce a new molecular theory beyond the Born-Oppenheimer approx imation, where both electrons and nuclei are treated quantum mechanica lly and equivalently. First, we develop the coupled mean-field theory (CMFT) for both the electronic and nuclear fields. Then, to take into account the dynamic correlation between these particles, we develop a new molecular theory using the generator coordinate method (GCM) based upon the CMFT, which enables us to calculate the molecular eigenstate and eigenvalue directly. Finally, we apply this method to a water mol ecule and analyze the isotope effect on the vibrational frequency and the particle density. (C) 1998 John Wiley & Sons, Inc.