Reply to Comment on the Two-lon Anisotropy in the Heavy-Rare-Earth Metals

The giant anisotropic two-ion couplings found in Er and Tb do not break the symmetry of the lattice. A nonspherical spin pressession due to crystal field effects was recently shown to induce such couplings from a basically isotropic interaction. The argument is here shown to be generally valid. It is shown that the conventional theory combined with the Hartree Fock approximation underestimates the effect of such ground-state corrections.