Van der Waals interaction between an atom and a small metalic sphere: Polarization induced by dispersive effect

The electric response held of a small metallic sphere to fluctuating dipola r and quadrupolar momenta is determined from spherical-tenser theory. This allows us to systematically describe the physisorbed atom polarization by i ntroducing the various dipolar and quadrupolar propagators between two poin ts outside the sphere. The non-local character of the electron response ins ide the sphere is included by using the random-phase approximation and by i ntroducing a Jellium model. Numerical application on the magnitude of the p hysisorbed atom polarization is presented for typical systems (Xe, Kr, Ar) on (Al, Cu, Ag).