Simple Model Calculations for Optical Constants of Copper

A simple s‐d band model is used for the interpretation of ϵ 2 (ω) for copper. Fitting simple polynomials for transition matrix elments, analytical expressions are obtained for ϵ 2 (ω) in terms of band parameters of the s‐d model. This expression is used to study the effect of matrix elements and variation of relaxation energy on ϵ 2 (ω) of copper. It is shown that such a simple model is sufficient to study such a variation and, therefore, to study the qualitative variation of ϵ 2 (ω). The model is also used to explain the peaks in dϵ 2 (ω)/dω curve successfully. The effect of hybridization amongst s and d bands is also taken into account for the calculation of transition matrix elements and the resulting effects in ϵ 2 (ω) are calculated.