The diagonal Born-Oppenheimer correction to molecular dynamical properties

We examine the effect of the diagonal Born-Oppenheimer correction on dynami cs in two simple systems - the Hooke's atom in an external harmonic potenti al and the collinear hydrogen exchange reaction. The transmission probabili ty for the Hooke's atom, calculated within the Born-Oppenheimer approximati on, is simply shifted in energy with respect to the exact result, and this is corrected by the diagonal adiabatic contribution. The reaction probabili ty for the H-3 system reflects the fact, that the diagonal Born-Oppenheimer correction raises the barrier to the reaction by approximately 70 cm(-1). (C) 2001 Elsevier Science B.V. All rights reserved.