Rihan, TH; Aly, NS; Merzbacher, E; Müller, B; Greiner, W, *Relaxation times in intermediate quasi-molecules*, vol. 285 no. 4
(1978),
pp. 397-403 [doi] .
**Abstract:**

*The influence of perturbative interactions is discussed in the frame-work of time-dependent perturbation theory. A characteristic time (to be called relaxation time), during which a given initial state of the system will be depleted, is defined. In case this relaxation time is smaller than the collision time of the process, the usual adiabatic perturbation treatment becomes vague. In this sense, the usefulness of various approaches to the problem, such as those based on two-center Dirac wave functions or Hartree-Fock states can be quantitatively investigated. Calculations based on two-center Dirac wave functions and a restricted quasimolecular configuration for the electronic system in U-U collisions, reveal that the electron-electron interactions can be safely neglected for the inner-shell electronic states. A prescription is given to obtain more reliable transition probabilities when the adiabatic perturbation treatment fails. It is shown that unitarity is recovered in such a prescription. © 1978 Springer-Verlag.*