Abstract
The results of the first totally ab initio calculation of the energy of a Takayanagi reconstruction, the 3 × 3 reconstruction on the Ge(111) surface, are presented. The energies of a number of elements of the Takayanagi reconstruction including the 3 × 3 structure without adatoms have also been calculated and the results are used to obtain information about the microscopic mechanism that is responsible for stabilising the Takayanagi structure. It is found that the addition of adatoms to form the complete Takayanagi structure leads to a large reduction in the energy of the surface and so it can be concluded that the adatoms play a crucial role in stabilising the Takayanagi reconstruction. The reduction in energy is attributed to a lowering of the surface stress.