Induced charge in ion-metal surface collisions

When an ion arrives at the metal surface, it produces an induced charge that affects formation of the ion-metal system electron states. The state promotion in a dipole field is discussed and measured electron energy spectra produced in multiply ion-metal collisions are explained using this model. The paper presents the results of calculating the electron density distribution of induced charge near the metal surface in the classical approach and also, quantum mechanically, with a variation model of a Density Functional Theory approximation. In the both cases the spatial cloud of induced charge is oblate parallel to the metal surface; in quantum mechanical solution the cloud is also shifted towards the approaching ion.