H-ZF13 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.73522\,\lambda^2}{\lambda^2 - 0.0131088} + \frac{0.316277\,\lambda^2}{\lambda^2 - 0.0621422} + \frac{2.16385\,\lambda^2}{\lambda^2 - 178.846}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-5.4 \times 10^{-6} + 2(1.34 \times 10^{-8})\,\Delta T + 3(-3.56 \times 10^{-11})\,\Delta T^2 + \frac{1.01 \times 10^{-6} + 2(1.25 \times 10^{-9})\,\Delta T}{\lambda - 0.291}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$