Model computations represent the effect of thermal vibration in the case of thermal energy He scattering from solid surfaces (TEAS). A time dependent one particle quantum mechanical model is applied solving the 3D time dependent Schrödinger equation[1][2]. The model contains a time dependent interaction potential that describes the fluctuating surface. The interaction potential is composed of a time independent and a time dependent perturbation part. The time independent part of the interaction potential corresponds to the frozen solid surface. The time dependent interaction potential describes the phenomena of the thermal vibration without energy transfer. There is no energy coupling between the probe particle and the surface in this model. The computations have been executed in the case of time independent and time dependent interaction potential, respectively. The thermal vibration causes a diffuse background of the intensity distribution. This effect changes the intensity pattern. The diffraction peaks remain sharp but their intensities decrease because of the diffuse background.

[1] G. Varga, Applied Surface Science, (1999) vol.144-145 p. 64-68.
[2] G. Varga, Surface Science, (1999) vol. 441 p. 472-478.