  The precipitation of energetic neutral atoms, produced through charge
exchange collisions between solar wind ions and thermal atmospheric gases, is
investigated for the Martian atmosphere. Connections between parameters of
precipitating fast ions and resulting escape fluxes, altitude-dependent energy
distributions of fast atoms and their coefficients of reflection from the Mars
atmosphere, are established using accurate cross sections in Monte Carlo
simulations. Distributions of secondary hot atoms and molecules, induced by
precipitating particles, have been obtained and applied for computations of the
non-thermal escape fluxes. A new collisional database on accurate
energy-angular dependent cross sections, required for description of the
energy-momentum transfer in collisions of precipitating particles and
production of non-thermal atmospheric atoms and molecules, is reported with
analytic fitting equations. 3D Monte Carlo simulations with accurate
energy-angular dependent cross sections have been carried out to track large
ensembles of energetic atoms in a time-dependent manner as they propagate into
the Martian atmosphere and transfer their energy to the ambient atoms and
molecules. Results of the Monte Carlo simulations on the energy-deposition
altitude profiles, reflection coefficients, and time-dependent atmospheric
heating, obtained for the isotropic hard sphere and anisotropic quantum cross
sections, are compared. Atmospheric heating rates, thermalization depths,
altitude profiles of production rates, energy distributions of secondary hot
atoms and molecules, and induced escape fluxes have been determined.
