[en] A time-dependent variational density functional method, based on the time-dependent Thomas-Fermi model (TDTF), for the description of collective dipole polarisation in ion-atom collisions is developed. H⁺-Ne scattering calculations at 6.25 and 25.0 keV indicate that while the quasi-adiabatic approach to the polarisation problem is appropriate in the first case, strong density oscillations are to be expected in the latter case. The characteristic eigenfrequencies of these outer-shell oscillations are comparable for Ne, Ar, Kr and Xe. (author)