[6]C is adsorbed parallel to the pristine surface, illustrated by a flat line in the ring height analysis presented in Figure ring heights for molecules on pristine surfaces, whereas orange, green, red, and purple diamonds are for substrates with one to four adatoms, respectively. Ring heights are relative to the adatom center of mass in the adatom surface, and the average z coordinate of the upper surface layer for the pristine substrates. Lines between symbols were added for ease of identification.