In GO1, GO2, and GO4 the functional group -COOH is attached to the C21 atom of graphene with an additional H atom attached to C8 for GO1, and to C11 for GO2. GO4 s similar to GO2 except that an -OH group replaces H at C11 and GO3 is similar to GO2 except that an OH group replaces the -COOH group at C21. In the GO5 model, the functional epoxy O atom straddles C21 and C8 atoms of graphene. All the GO models are twisted and inclined away from the planar graphene structure at the point of attachment to the functional in both ground and triplet states. (ZnO) 3 adsorption on graphene and graphene oxides GO1-GO5