Semiquantum approach for fast atom diffraction: Solving the rainbow divergence

Abstract

In this work we introduce a distorted-wave method, based on the initial value representation approach of the quantum evolution operator, in order to improve the description of rainbow effects given by the surface eikonal (SE) model for diffraction from crystal surfaces produced by grazing scattering of fast atoms. The proposed theory, named the surface initial value representation (SIVR) approximation, is applied to He atoms colliding with a LiF(001) surface along low-indexed crystallographic channels. For this collision system the SIVR approach provides a very good representation of the quantum interference structures of experimental projectile distributions, even in the angular region around classical rainbow angles where the semiclassical SE method diverges.