Deviations from the adiabatic approximation in heavy-ion dynamic polarization potentials

The dynamic polarization potential induced by the coupling to excited states in a heavy ion collision is investigated. The dynamic polarization potential operator is defined in a semi-classical framework: its integral along the classical trajectory is given by the second-order amplitude corresponding to the coupling to the intermediate state and back. Moreover, it is assumed that the excitation energy is larger than h divided by the time of the collision; Under these approximations, an expansion of the real part of the polarization potential in inverse powers of the excitation energy is obtained. The lowest-order term, which is inversely proportional to the excitation energy, is the usual adiabatic polarization potential. The next term, inversely proportional to the square of the excitation energy, contains spin-orbit terms, and also rank-3 polarization potentials.. (C) 2003 Elsevier B.V. All rights reserved.