atom 4d4d atomic orbitals. There are five 4d orbitals. These are labelled 4d xy, 4d xz, 4d yz, 4d x 2-y 2 and 4d z 2. The 4d z 2 name is an abbreviation for 3d (3z 2 –rAtom Array. Basic Coord. Object. Basic Properties Icon Settings. Icon File ID. Sometimes, when working with numerous icons that look the same, you want to have a better overview of it all.