Column density profiles of CH₃OH (left) and N(CH₂DOH)/N(CH₃OH) profiles (right) of various diffusive models, that we used to test different approaches to prohibit an unphysical buildup of H₂ on the surface of dust grains. A reference model (BE1) without a H₂ removal method is shown. Additionally, we present a model (D4), where the binding energy of H₂ and its isotopologues were scaled by 0.1 and several models adopting the H₂ removal method proposed by Garrod & Pauly (2011) applied to all species (BE2), only to H₂ (BE3) and only to H and H₂ (BE4). The observed profiles are depicted in black (errors as grey-shaded areas).