Geometry of the H
/graphene/Ni(111) systems investigated in this study. Graphene layer is arranged in the top-fcc configuration on Ni(111). Adsorbed molecules can be placed in three different highly symmetric adsorption sites: T, on-top; B, on-bond; C, center, with respect to the graphene lattice. Two examples of adsorption are shown: for NH3 in the on-top position with hydrogen atoms directed to the neighboring carbon atoms, and for H2O in the center position with hydrogen atoms directed to the C-C bonds.