Polaron effects on electronic properties of metal/medium interfaces .1. Uncharged metal/dielectric and metal/electrolyte interfaces

A new approach to the electron density functional description of the metal/dielectric interface is suggested. The role of the fast and slow polarisation modes of the dielectric medium in determining the ground-state electronic properties of the interface is elucidated. It is shown that the electrostatic energy term of the electron density functional contains the screening by the total dielectric polarisation held (static relative permittivity) whereas the exchange-correlation energy is screened only by the high-frequency polarisation (optical dielectric constant). Manifestation of these effects in the free electron density distribution near the uncharged interface and in related observables, such as surface energies and workfunctions, is investigated using the Kohn-Sham scheme and the trial function approach.