Sticking coefficients of Molecular Hydrogen on Amorphous Ice using Molecular Dynamics Simulations

The Molecular Dynamics (MD) method was employed to model hydrogen molecules interacting on the surface of amorphous ice and the sticking coefficients of H$_2$ were calculated. Interstellar dust grains are mostly composed of carbon or silicate grains with layers of amorphous ice on their surface. Interaction of molecular hydrogen with these grain surfaces is of astrophysical importance as the gas-grain interactions play a pivotal role in the chemical evolution of the universe. Our model implements the various dynamical processes that occur during the interaction of the H$_2$ molecules on the amorphous ice surface, including the random angle striking of H$_2$ on the surface, scattering of H$_2$, and sticking of H$_2$ to the surface. The temperature of the dust grains (T$_D$) and H$_2$ molecules (T$_{H_2}$) play an important role in the surface interactions and in the sticking process. We studied the sticking coefficients as a function of temperature distribution of T$_D$ and T$_{H_2}$.