The traditional hard-disk Lorentz gas describes the chaotic motion of a classical point particle through an array of impenetrable disks. Soft-disk modifications of the two-dimensional Lorentz gas, where the scattering particle can move into the disk interiors, are considered here. Conditions on the soft-disk potentials and disk separations that guarantee chaotic motion are obtained.

• Received 22 December 2000

DOI:https://doi.org/10.1103/PhysRevE.63.066216