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

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 ℏ 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.