“…Under such assumptions we are neglecting the dispersion ε 2 and σ 2 along OZ, which is, generally speaking, true for metal films with the thickness 2δ that satisfies the condition 2δk F ∼ 1 ÷ 10, where k F = ( 3 4π ) 2 3 r s a −1 0 , r s is Gell-Mann-Brakner parameter, a 0 is Bohr raduis [6,7] and the influence of fringe effects in the XOY plane (this is true when geometric dimensions of a metal film in XOY are considerably larger than its thickness along OZ, 2δ( √ S) −1 ≪ 1, where S is an area of the metal film surface).…”