We reconsider the results of Lontano and Raimondi [Phys. Rev. E 51, R2755 (1995)] within the full random-phase approximation. We show that the correlation and also velocity dispersion of the cluster ions enhance and reduce the stopping power, respectively. Nevertheless, the enhancement of energy losses due to ionic correlation is much stronger than that obtained by Lontano and Raimondi, and furthermore, the projectile velocity dependence of the stopping power is strictly monotonic, presenting no oscillations. We also did not obtain negative values for the cluster stopping power, as did Lontano and Raimondi.

• Received 26 July 1996

DOI:https://doi.org/10.1103/PhysRevE.56.6208