Modelling of the optical properties of silver with use of six fitting parameters

We propose a realistic model of the optical properties of silver, in which inter-band transition with a threshold energy of ~ 4 eV is described phenomenologically by an ensemble of oscillators with same damping constant and a certain distribution of resonant frequencies in the interband transition threshold to infinity. The contribution of the conduction electrons in the dielectric function is determined by the Drude formula. The proposed model actually contains the features of both the Drude-Lorentz model (Raki\'c et al. 1998) and Tauc-Lorentz model (Jian-Hong Qiu et al. 2005). However, unlike these works proposed model contains only six fitting parameters, with the square root of the mean square deviation of the absorption coefficient and refractive index of silver from the experimental values in the range of 0.6 nm - 6.0 nm being of the order of 0.05.