We have used the dynamical theory of low-energy electron diffraction to analyze data of the Si(111)7×7 surface and determined the atomic structure. The method includes the use of symmetrized wave functions in real and reciprocal spaces. Individual atomic coordinates for the first five atomic planes (containing 200 atoms) are determined. The low-energy electron diffraction optimized structure shows an oscillatory relaxation: atomic planes with stretched bonds followed by planes with compressed bonds. Geometric displacements from the bulk dimer–adatom–stacking fault model are presented.