Decoherent phonon effects in fast atom-surface scattering

Understanding the influence of phonon-mediated processes on grazing-incidence fast atom diffraction (GIFAD) patterns is relevant for its use as a surface analysis technique. In this work, we apply Phonon-Surface Initial Value Representation (P0-SIVR) approximation to study lattice vibration effects GIFAD He-LiF(001) system at room temperature. The P0-SIVR approach semiquantum method that describes zero-phonon atom-surface scattering including contribution intermediate phonon transitions. main features introduced by thermal vibrations in angular distributions scattered helium atoms are investigated considering normal energies 0.1 -3 eV range. all cases, fluctuations introduce wide polar spread transforms interference maxima into elongated strips. We found width these fringes does not depend energy, it was experimentally observed. addition, when energy increases, only relative intensities peaks affected crystal vibrations, but also visibility structures, which disappear completely approximately equal or higher than 3 eV. These findings agree fairly well with experimental data reported Phys. Chem. 237615 (2021). However, should be noticed simulated widths underestimate experimentally-derived limit, suggesting there other mechanisms, such inelastic processes, contribute dispersion patterns.