We report an experimental refinement of the local charge density at the Si (111) 7x7 surface utilizing a combination of x-ray and high energy electron diffraction. By perturbing about a bond-centered pseudoatom model, we find experimentally that the adatoms are in an anti-bonding state with the atoms directly below. We are also able to experimentally refine a charge transfer of 0.26(4) e- from each adatom site to the underlying layers. These results are compared with a full-potential all-electron density functional DFT calculation.
@article{arxiv.0901.3135,
title = {Charge Density Refinement of the Si (111) 7x7 Surface},
author = {J. Ciston and A. Subramanian and I. K. Robinson and L. D. Marks},
journal= {arXiv preprint arXiv:0901.3135},
year = {2015}
}