NOVEL ADIABATIC INVARIANT FOR THE 3-BODY COULOMB PROBLEM

The two-(fixed) center Coulomb problem possesses in nonrelativistic me chanics, besides the ''classical'' constants of motion, an additional constant of motion associated with dynamical symmetry and separability of the problem. When the motion of the nuclei is taken into account t he constant of motion is destroyed but reappears as an adiabatic invar iant. We have identified this novel adiabatic invariant for the unrest ricted three-body problem in the limit of two heavy particles and one light particle. Unlike all other known adiabatic invariants, it is glo bally conserved to order delta = m/M in the light- to heavy-mass ratio . The significance of this invariant for the semiclassical description of the chemical bond and for diatomic molecules beyond the Born-Oppen heimer approximation is discussed. (C) 1995 American Institute of Phys ics.