Tetrahedral complexes are the second most common type; here four ligands form a tetrahedron around the metal ion. In a tetrahedral crystal field splitting, the d -orbitals again split into two groups, with an energy difference of Δ tet. The lower energy orbitals will be d z and d x - y, and the higher energy orbitals will be d xy, d xz and d yz - opposite to the octahedral case. Furthermore, since the ligand electrons in tetrahedral symmetry are not oriented directly towards the d -orbitals, the energy splitting will be lower than in the octahedral case. Square planar and other complex geometries can also be described by CFT.