Pérez García, Victor M.. 

We argue that the classical form of the dipole–dipole interaction energy cannot be used to model the interaction of the bosons in a dilute Bose–Einstein condensate made of polar atoms. Mathematically, the reason is the lack of convergence of the associated integrals if no additional restrictions are introduced. The problem can be regularized, in particular, by introducing a hard sphere model. As an example we propose a regularization consistent with the long range behavior of the effective potential and with the scattering amplitude of the fast particles.