The van der Waals interaction between two polarizable atoms is considered. In three dimensions the standard form with an attractive $1/|R|^6$ potential is obtained from second-order quantum perturbation theory. When the electron motion is restricted to lower dimensions (but the $1/|R|$ Coulomb potential is retained), new terms in the expansion appear and alter both the sign and the $|R|$ dependence of the interaction.
Categories: quant-ph cond-mat.mes-hall