Solid State Physics. Philip Hofmann

moment arises in one atom at some time. This can be modeled as two point charges separated by a distance . This electric dipole gives rise to an electric field , by which the other atom is polarized such that a dipole moment is induced in this second atom. is proportional to the field, that is, [see Eq. (9.4)]. The potential energy of an electric dipole in an electric field is . Therefore, all you need to show is that the electric field caused by the dipole in the first atom decays as for .

Note

      1 1 For the full calculation, see online note on www.philiphofmann.net.