Interaction potentials for atoms in front of a LiF(001) surface

M.S. GRAVIELLE; J.E. MIRAGLIA; G.A. BOCAN

Book Series "Interdisciplinary Research on Particle Collisions and Quantitative Spectroscopy"

World Scientific

Año: 2019;

We present precise representations of the atom-LiF(001) interaction forboth multielectronic and hydrogen atoms. For the former we introducea pairwise additive (PA) potential model that includes an improved de-scription of the electron density associated with the different lattice sites,as well as non-local electron density contributions. We apply this PAmodel to evaluate the interaction potential between closed-shell - He, Ne,Ar, and Kr - and open-shell - N, S, and Cl - atoms and the LiF surface.In turn, for H projectiles we build a high-precision interaction potentialfrom density functional theory calculations, which properly takes intoaccount the reactivity of the H-LiF(001) system, including the contribu-tion of van der Waals (vdW) forces.The performance of the proposed potentials is assessed by contrast-ing angular projectile distributions produced by fast grazing incidencewith available experimental data. For multielectronic projectiles, the an-gular positions of rainbow and supernumerary rainbow maxima derivedwithin the PA potential are in good agreement with the experiments,confirming the validity of the potential model in a wide normal energyrange, from 0.2 to 80 eV. In all the cases vdW contributions are esti-mated as negligible. In contrast, for H atoms the comparison of oursimulations with experimental grazing-incidence fast atom diffractionpatterns strongly suggests a non-negligible role of vdW interactions inthe low normal energy regime when incidence is along the <100> channel.