we calculated the imaginary part of the longitudinal permittivity of thin gold films. It was found that in the region of 0.5 eV, a peak in permittivity is observed, and with increasing thickness (2-5 nm) of the film with the (111) surface, this peak increased significantly (from 4 to 
, while for films with other surfaces (100) and (110), the opposite picture was observed.
It is unclear why such different behaviors of the imaginary part of the longitudinal permittivity are observed!!
The influence of the parameters of the vacuum gap (approximately 50 A), the number of empty zones, the number of k-points, and the NGZ(F) value were checked. None of these parameters significantly changed the imaginary part of the longitudinal permittivity.