Fast atom diffraction for grazing scattering of Ne atoms from a LiF(001) surface

Semiquantum approach for fast atom diffraction: Solving the rainbow divergence

“…Within this model, successfully employed in FAD from insulator surfaces [20,21], the surface-projectile potential takes into account the static and polarization contributions. The static potential, derived by assuming that the electronic densities of the particles remain frozen during the collision, was evaluated as the sum of the electrostatic, kinetic and exchange potentials [36].…”

“…The static potential, derived by assuming that the electronic densities of the particles remain frozen during the collision, was evaluated as the sum of the electrostatic, kinetic and exchange potentials [36]. While in previous articles [20,21] only local electronic density contributions were considered, in this paper we incorporate no local terms to evaluate the kinetic and exchange potentials, as given by the Lee-Lee-Parr [37] and Becke [38] models, respectively. In turn, the polarization potential, due to the rearrangement of the projectile electron density induced by the presence of target ions, was derived as in Ref.…”

“…But for higher perpendicular energies, like the ones considered in Figs. 2 and 3, discrete Bragg peaks originated from the interference of trajectories from different reduced unit cells are not present in the experimental distributions due to the limits in spatial resolution of the detector [21]. Therefore, only supernumerary rainbow contributions are visible in the experimental spectra of such figures.…”

Ab initiopotential for the He-Ag(110) interaction investigated using grazing-incidence fast-atom diffraction

“…As it is the case with all diffraction techniques, these interference structures stem from two different contributions, the structure factor, responsible for the presence of the Bragg peaks, and the form factor, responsible for the intensity variations. Both mechanisms can be separately analyzed within the SE model by factorizing the transition matrix as [23] where T (SE) 1 (Q tr ) is derived from Eq. (1) by evaluating the R os integral over one reduced unit cell.…”

“…The SE approach is a semiclassical approximation that includes a clear description of the main mechanisms of the process. It has been successfully applied to investigate fast-atom diffraction from insulator surfaces [21][22][23]. In contrast to other approaches [24,25], the corrugation of the complete 3D PES is taken into account without averaging the projectile-surface potential along the incidence direction.…”