  An extended elastic eigenvector approach for adatom interactions is applied
to elastically isotropic substrates. The oscillating interactions between
adatom monomers or dimers are caused by strain fields in the substrate.
Expansive or contractive strain fields are surrounding adatoms in form of quasi
circular rings. The exact shape of the ring structure depends on the elastic
constants of the substrate and especially on the surface Brillouin zone.
Interactions on isotropic substrates are depicted and compared with an
anisotropic example. Overlays of 2-D plots can help to identify adatom
structures caused by elastic effects and to prepare numerical calculations of
their elastic energies. The consequences of different sorts of adatoms with
different interaction sign are sketched, large short distance attraction could
occur in such cases. Limitations of the method are discussed and possible
applications are formulated.
