We examine the small-energy cross section behaviour for the process e + H -~ H * + 2e. The excitation-detachment function appears approximately constant above the classical threshold, with a weak undulatory component superimposed. The energy distribution function for the outgoing electrons is found almost uniform within our classical model.

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We have detected an error in Fig. 1. The analytical expression for the detachment function, taken over from [11], ff~E 9/4 exp {-16.4]/E } should read cr~E 9/4 exp { -16.4//E }. The error stems from (28a) in [-11], where apparently due to a missprint, sign "-" in front of the exponent "1/2" is missing, what can be easily inferred from (27a) from the same reference [cf. also (29)]. As a curve drawn according the correct analytical expression appears practically stepfunction-like (going vertically to infinity), at an arbitrarily chosen point on the abscise, it bears no resemblance to our numerical results, calculated for the excitation-ionization intervals.Since, however, detachment function from [-111 was used only for the sake of comparison, in absence of any other data for the excitation-ionization function, it is of no crucial importance to our calculations and final results and should be ignored in Fig. 1 of our paper. The same holds for the corresponding comments in the text.We complete the Reference list here:10.

Wannier's classical theory has been successfully applied to studies of fragmentation functions when the interaction potential was homogeneous. Here, the methods of classical mechanics are applied to cases with a non-homogeneous interaction potential. In this case an analytic solution is not available. However, the numerical solution can be fitted to an analytic expression. A system is discussed that in its final state consists of a highly excited atom, an electron and a positron (A*+e-+e+). The interaction potential consists of the Coulomb term plus monopole to quadrupole and/or polarisation terms.Near threshold, the cross section is fitted to the form U = aE". Results are given for H and He.

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