  The event-by-event Monte Carlo code, TREKIS, was recently developed to
describe excitation of the electron subsystems of solids in the nanometric
vicinity of a trajectory of a nonrelativistic swift heavy ion (SHI) decelerated
in the electronic stopping regime. The complex dielectric function (CDF)
formalism was applied in the used cross sections to account for collective
response of a matter to excitation. Using this model we investigate effects of
the basic assumptions on the modeled kinetics of the electronic subsystem which
ultimately determine parameters of an excited material in an SHI track. In
particular, (a) effects of different momentum dependencies of the CDF on
scattering of projectiles on the electron subsystem are investigated. The
'effective one-band' approximation for target electrons produces good
coincidence of the calculated electron mean free paths with those obtained in
experiments in metals. (b) Effects of collective response of a lattice appeared
to dominate in randomization of electron motion. We study how sensitive these
effects are to the target temperature. We also compare results of applications
of different model forms of (quasi-) elastic cross sections in simulations of
the ion track kinetics, e.g. those calculated taking into account optical
phonons in the CDF form vs. Mott's atomic cross sections. (c) It is
demonstrated that the kinetics of valence holes significantly affects
redistribution of the excess electronic energy in the vicinity of an SHI
trajectory as well as its conversion into lattice excitation in dielectrics and
semiconductors. (d) It is also shown that induced transport of photons
originated from radiative decay of core holes brings the excess energy faster
and farther away from the track core, however, the amount of this energy is
relatively small.
