  A micromechanical model based on the theory of elasticity has been developed
to study the configuration of self-assembled impurity nanostructures in high
temperature superconducting YBCO films. With the calculated equilibrium strain
and elastic energy of the impurity doped film, a phase diagram of lattice
mismatches $vs.$ elastic constants of the dopant was obtained for the
energetically-preferred orientation of impurity nanorods. The calculation of
the nanorod orientation and the film lattice deformation has yielded an
excellent agreement with experimental measurements.
