Thermal energy atomic scattering on solid surfaces (TEAS) provides information about the very top layer of the solid surfaces, because the probe particle (usually He atoms) do not penetrate into the surface. The dynamics of the atom - solid surface interaction is a fundamental question. This problem is discussed within the frame of a classical model in case of He-Rh(311) system. The mass point of the He atom scatters according to an appropriately chosen interaction potential. This interaction describes the solid surface. The motion ot the particle mass point is governed by Newton's laws. The He atoms scattering according to the interaction potential of the He - Rh(311) system¹ is discussed as a function of impact parameter. Detailed computations show trapping on surface and 3D chaotic effects in trajectories as well as phase diagrams, deflection angle function and dwell time function. The crucial point of the above described model is the numerical method to solve the system of differential equations. For stiff problems - as the present ones - the variable solver based on differentiation formulas are recommended².

1. R. Apel, D Farías, H. Tröger, E. Kristen, K.H. Rieder, Surface Science 364 (1996) p. 303.
2. Shampine, L.F. and M.W. Reichelt, SIAM Journal on Scientific Computing, Vol. 18-1, (1997).