A calculation is performed of ion-velocity and energy-distribution functions in plasma occupied by ion-acoustic compressive and rarefactive solitons. The pseudopotential method and ergodic hypothesis are used. A two-electron model of plasma with cold ions is considered. Formulas valid for arbitrary amplitude are obtained. It is shown that the perturbed distribution functions have a beamlike form. The results are compared with previously obtained analytical calculations and modeling results.
Trukhachev et al. (Sun,) studied this question.