  Recent experiments have revealed the possibility of precise electron beam
manipulation of silicon impurities in graphene. Motivated by these findings and
studies on metal surface quantum corrals, the question arises what kind of
embedded Si structures are possible within the hexagonal lattice, and how these
are limited by the distortion caused by the preference of Si for $sp^{3}$
hybridization. In this work, we study the geometry and stability of elementary
Si patterns in graphene, including lines, hexagons, triangles, circles and
squares. Due to the size of the required unit cells, to obtain the relaxed
geometries we use an empirical bond-order potential as a starting point for
density functional theory. Despite some interesting discrepancies, the
classical geometries provide an effective route for the simulation of large
structures.
