  We report first-principles calculations of the energetics and simulated
scanning tunneling microscopy (STM) images for Mn dopants near the GaAs (110)
surface, and compare the results with cross-sectional STM images. The Mn
configurations considered here include substitutionals, interstitials, and
complexes of substitutionals and interstitials in the first three layers near
the surface. Based on detailed comparisons of the simulated and experimental
images, we identify three types of Mn configurations imaged at the surface: (1)
single Mn substitutionals, (2) pairs of Mn substitutionals, and (3) complexes
of Mn substitutionals and interstitials.
