H-ZBAF1 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.05607\,\lambda^2}{\lambda^2 - 114.46} + \frac{1.45457\,\lambda^2}{\lambda^2 - 0.00840268} + \frac{0.129036\,\lambda^2}{\lambda^2 - 0.0363054}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[2.79 \times 10^{-6} + 2(1.8 \times 10^{-8})\,\Delta T + 3(-3.67 \times 10^{-11})\,\Delta T^2 + \frac{5.85 \times 10^{-7} + 2(3.27 \times 10^{-10})\,\Delta T}{\lambda - 0.191}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$