H-ZF12 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.32373\,\lambda^2}{\lambda^2 - 0.0598308} + \frac{1.65669\,\lambda^2}{\lambda^2 - 0.0120543} + \frac{2.12142\,\lambda^2}{\lambda^2 - 174.188}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-3.47 \times 10^{-6} + 2(1.41 \times 10^{-8})\,\Delta T + 3(-2.09 \times 10^{-11})\,\Delta T^2 + \frac{8.94 \times 10^{-7} + 2(1.27 \times 10^{-9})\,\Delta T}{\lambda - 0.3}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$