H-ZF1 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.06294\,\lambda^2}{\lambda^2 - 108.4} + \frac{0.146911\,\lambda^2}{\lambda^2 - 0.0591797} + \frac{1.48923\,\lambda^2}{\lambda^2 - 0.0115933}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-4.73 \times 10^{-6} + 2(1.27 \times 10^{-8})\,\Delta T + 3(-8.17 \times 10^{-11})\,\Delta T^2 + \frac{8.61 \times 10^{-7} + 2(9.43 \times 10^{-10})\,\Delta T}{\lambda - 0.263}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$