Thermal energy atomic scattering (TEAS) is an efficient surface tool because it is sensitive for the very top layer of the surface [1]. TEAS has extremely large cross section in the case of any disorders of the surface [2]. This fact provides the facility of TEAS to measure an average description of surface disorder. Present work investigates this facility by a quantum mechanical model that describes the atomic beam as an appropriate Gaussian wave packet [3][4][5]. The surface disorders embed in the atom-surface interaction potential. The atom-surface interaction is governed by 3D time dependent Schrödinger equation. The main problem that how the distribution of disorders can be considered in the above mentioned model. The results try to resolve the contradiction that the Gaussian wave packet probes small (local) region of the surface, however the real experimental of TEAS provides an average of the distribution of the disorders.

[1] D. Farías and K.H. Rieder, Rep. Prog. Phys. Vol. 61 (1998) 1575-1664.

[2] B. Poelsema and G. Comsa, Scattering of thermal energy atoms from disordered surfaces, Springer-Verlag 1989.

[3] G. Varga, Applied Surface Science, (1999) vol.144-145 p. 64-68.

[4] G. Varga, Surface Science, (1999) vol. 441 p. 472-478.

[5] G. Varga, Home Page, Scattering animations (2000): http://goliat.eik.bme.hu/~vargag/