  Using classical molecular dynamics simulations we examine the formation of
craters during 0.4 - 100 keV Xe bombardment of Au. Our simulation results, and
comparison with experiments and simulations of other groups, are used to
examine to what extent analytical models can be used to predict the size and
properties of craters. We do not obtain a fully predictive analytical model
(with no fitting parameters) for the cratering probability, because of the
difficulty in predicting the probability of cascades splitting into
subcascades, and the relation of the heat spike lifetime and energy density. We
do, however, demonstrate that the dependence of the crater size on the incident
ion energy can be well understood qualitatively in terms of the lifetime of the
heat spike and the cohesive energy of the material. We also show that a simple
energy density criterion can not be used to predict cratering in a wide ion
energy range because of the important role of the heat spike lifetime in
high-energy cascades. The cohesive energy dependence differs from that obtained
for macroscopic cratering (observed e.g. in astrophysics) because of the
crucial role of melting in the development of heat spikes.
