  The neutralization probability of low energy Na$^{+}$ ions scattered from In-
and As-rich InAs(001) surfaces is measured by time-of-flight spectroscopy. It
is found that the neutralization probability for projectiles scattered from As
sites is larger than from In sites for both types of surfaces. A modification
of the resonant charge transfer model is proposed in which a freezing contour
that follows the atomic structure is combined with molecular dynamics and
density functional theory. Together, these approaches show that the
neutralization of alkali projectiles scattered from a compound solid material
is determined by multiple factors, particularly the surface atomic and
electronic structures. This model is applicable to any system in which the
surface potential is inhomogeneous, such as compound materials and
adsorbate-covered surfaces.
