ON THE ADIABATIC SEPARATION OF THE VIBRATIONAL VARIABLES OF A HYDROGEN-BONDED AHA FRAGMENT WITH A SYMMETRICAL DOUBLE-WELL POTENTIAL

The adiabatic separation of the vibrational variables of a hydrogen-bo nded AHA fragment with a symmetric double-well potential is considered using two approaches. In the first approach the A...A stretch vibrati on is slow in comparison to the proton vibration. It is applicable to the energy level calculations of an AHA fragment with a potential barr ier of arbitrary height. In the alternative approach the proton is con sidered to be a ''slow'' subsystem. This approach appears to be of lim ited applicability. For an AHA fragment with a symmetric double-well p otential the Born-Oppenheimer criterion is shown to contain the freque ncy corresponding to the proton 0 --> 2 transition in both approaches.