Another distinctive pattern observed in the ID-containing systems was concave surface transitions. They typically consisted of a 210° angle between {110} and {100} surfaces with the exposure of a 5-fold Mg 2+ cation at the edge. The main reason for their appearance is to balance the overall surface morphology when many sharp edges are present, maintaining an energetically feasible shape. In addition, these concavities can also serve as an adsorption site to octahedral TiCl4: TiCl4 adsorbs on a short {110} terrace involving a 3-fold Mg 2+ cation at an edge and a 5-fold Mg 2+ cation at a concavity. Adsorption of TiCl4 on concave surfaces was reported to be energetically favorable on ideal surfaces, and here its occurrence was confirmed in realistic clusters as a result of the ID-driven MgCl2 reconstruction.