The goal of surface scattering simulations is to accurately model how molecules interact with surfaces.  This is a daunting challenge because molecule-surface interactions can result in many different processes including: dissociation, scattering, and various excitations.  Currently most molecule-surface interactions are modeled using the Born-Oppenheimer approximation which limits the reaction to one potential energy surface (PES).  However, the BO approximation does not generally hold for non-adiabatic processes.  Recent research has studied whether or not there are certain reactions that can be accurately described using the BO approximation.  In general the BO approximation has proven fairly accurate for light molecules (i.e. H₂) but heavier molecules tend to experience other surface-interactions that affect its scattering such as phonon excitation and electron-hole excitation.  These scenarios ideally should be modeled using a diabatic PES or multiple PESs which is not the case with the Born-Oppenheimer.  Many challenges remain in this field including: developing an accurate method to model interactions in the electronic ground state, excited electronic states, as well as accurately describing the effects of phonon excitation.  Overall the article does not discuss surface scattering as much as I expected.  Rather it focused heavily on modeling phonon and electron-hole excitations.  These do present a challenge to calculating accurate scattering simulations, but I expected more discussion on how scattering interactions (vibrational, rotational, and diffractive) are calculated.

Reference: Kroes, Science, 321, 794-797, 2008