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 –rWe will use the Atomic Simulation Environment (ASE) package to manipulate and visualize atomic models of the samples we will simulate. Periodic unit-cells ¶ The main object