Different reconstructions can also occur depending on the substrate and adsorbate coverages and the ambient conditions, as the equilibrium positions of the atoms are changed depending on the forces exerted. One example of this occurs in the case of In adsorbed on the Si (111) surface, in which the two differently reconstructed phases of Si(111) 3 × × 3 -In and Si(111) 31 × × 31 -In (in Wood's notation, see below) can actually coexist under certain conditions. These phases are distinguished by the In coverage in the different regions and occur for certain ranges of the average In coverage.