Figure 4

Imaginary part of the dielectric function of (a) TaAs, (b) TaP, (c) NbAs, and (d) NbP for light polarization perpendicular (black solid lines) and parallel (red dashed lines) to the tetragonal axis. The lorentzian broadening parameter used is 0.05 eV. The insets (calculated with a higher k-point density and a lorentzian broadening of 0.01 eV) show the asymptotic behavior for ω → 0.