  Grazing-incidence fast atom diffraction (GIFAD) is an exceptionally sensitive
method for surface analysis, which can be applied not only at room temperature
but also at higher temperatures. In this work we use the He-LiF(001) system as
benchmark to study the influence of temperature on GIFAD patterns from
insulator surfaces. Our theoretical description is based on the Phonon-Surface
Initial Value Representation (P0-SIVR) approximation, which is a semiquantum
approach that includes the phonon contribution to the elastic scattering.
Within the P0-SIVR approach the main features introduced by thermal lattice
vibrations on the angular distributions of scattered projectiles are
investigated as a function of the crystal temperature. We found that azimuthal
and polar spectra are strongly affected by thermal fluctuations, which modify
the relative intensities and the polar spread of the interference structures.
These findings are relevant for the use of GIFAD in surface research. Moreover,
the present results are contrasted with available experimental data at room
temperature.
