The properties of an As vacancy on the (110) surface were studied by using a first-principles pseudopotential method. It was found that the relaxed atomic structure involved an inward movement of the neighboring surface Ga atoms. This did not agree with scanning tunnelling microscopic images. On the other hand, a more careful analysis yielded excellent agreement with experimentally determined scanning tunnelling microscopic images.

H.Kim, J.R.Chelikowsky: Physical Review Letters, 1996, 77[6], 1063-6