  In recent experiments the irradiation of insulators of perovskite type with
swift heavy ions under glancing incidence has been shown to provide a unique
means to generate periodically arranged nanodots at the surface. The physical
origin of these patterns has been suggested to stem from a highly anisotropic
electron density distribution within the bulk. In order to show the relevance
of the electron density distribution of the target we present a model
calculation for the system Xe$^{+23}$ $\to$ SrTiO$_{3}$ that is known to
produce the aforementioned surface modifications. On the basis of the Lindhard
model of electronic stopping, we employ highly-resolved \emph{ab-initio}
electron density data to describe the conversion of kinetic energy into
excitation energy along the ion track. The primary particle dynamics are
obtained via integration of the Newtonian equations of motion that are governed
by a space- and time-dependent friction force originating from Lindhard
stopping. The analysis of the local electronic stopping power along the ion
track reveals a pronounced periodic structure. The periodicity length strongly
varies with the particular choice of the polar angle of incidence and is
directly correlated to the experimentally observed formation of periodic
nanodots at insulator surfaces.
