Dynamical properties of molecules physisorbed on a metal particle

The response potential of a small metallic sphere to a fluctuating dipole moment is determined from spherical-tensor theory. The non-local character of the electron response is included by using the random-phase approximation and by introducing a jellium model. The response field obtained from this calculation allows us to define a new expression of the effective linear polarisability of a molecule physisorbed on a metal particle. Two limiting cases are then considered: the dielectric approximation and the non-local homogeneous one.