Supplementary Materials for "Depolarization and polarization transfer rates for the C$_2$$(X ^1\Sigma^+_g, a ^3\Pi_u)$ + H$(^2S_{1/2})$ collisions in the solar photosphere"

The file "C2H_PESs.txt" holds results of ab initio calculation of the potential energy surfaces (PESs), V(R,θ) in units of cm^-1, arrising from the interaction of hydrogen atom H in its ground electronic state, $^2S$, with C$_2$ molecule its lowest energy state, ($X^1\Sigma^+_g$), (the resulting electronic state $1 \; ^2A'$ ,  E1) and with C$_2$ molecule in its second-lowest energy state, ($a ^3\Pi_u$), (the resulting electronic state $2 \; ^2A'$ & $2 \; ^2A''$,  E2 & E3, respectively). Here R represents the distance (in atomic units) from the center of mass of the C$_2$ molecule to the H atom, and the angle $\theta$ (in degrees) defines the rotation of the H atom around the C$_2$ molecule. All the PESs are obtained using the MOLPRO package (e.g. Werner et al. 2010).

The files "C2H_Sigma_0toK_SIGMA_STATE.csv" and "C2H_Sigma_0toK_PI_STATE.csv" contain results of the infinite-order sudden approximation (IOS) calculation of cross sections, $\sigma(0 \to K)$ in units of $\mathring{\mathrm{A}}^2$, as functions of energy in units of cm$^{-1}$ for the collisions C$_2$ $(X ^1\Sigma^+_g)$ + H$(^2S_{1/2})$ and C$_2$ $(a ^3\Pi_u)$ + H$(^2S_{1/2})$, respectively. The IOS cross sections are calculated using MOLSCAT code (Hutson & Green 1994). The depolarization and transfer of polarization cross sections can be calculated from the IOS cross sections via Eqs. (2) & (3) of the related manuscript.