H-ZK8 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.60095\,\lambda^2}{\lambda^2 - 5.19864 \times 10^{-11}} + \frac{0.958289\,\lambda^2}{\lambda^2 - 0.0167563} + \frac{1.1406\,\lambda^2}{\lambda^2 - 133.109}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-4.06 \times 10^{-6} + 2(1.94 \times 10^{-8})\,\Delta T + 3(-4.18 \times 10^{-11})\,\Delta T^2 + \frac{5.96 \times 10^{-7} + 2(6.67 \times 10^{-11})\,\Delta T}{\lambda - 0.184}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$