Extending holographic LEED to ordered small unit cell superstructures
  Following on the success of the recent application of holographic LEED to the determination of the 3D atomic geometry of Si adatoms on a SiC(111) p(3x3) surface, which enabled that structure to be solved, we show in this paper that a similar technique allows the direct recovery of the local geometry of adsorbates forming superstructures as small as p(2x2), even in the presence of a local substrate reconstruction. 
K. Reuter, J.A. Vamvakas, D.K. Saldin, V. Blum, M. Ott, H. Wedler, R.   Doell, and K. Heinz