A similar result holds for Hermitian centrosymmetric and skew-centrosymmetric matrices. It is worth noting that all the even order susceptibilities become zero in centrosymmetric media. In crystallography, the presence of inversion centers distinguishes between centrosymmetric and noncentrosymmetric compounds. The carbon dioxide molecule is linear and centrosymmetric. Symmetric centrosymmetric matrices are sometimes called bisymmetric matrices. An important point about ferroelectrics is that they cannot exist in a centrosymmetric crystal. The same rule also applies to "f-f" transitions in centrosymmetric complexes of lanthanides and actinides. Hence, in a centrosymmetric molecule, IR and Raman spectroscopy are mutually exclusive. Since it is centrosymmetric, the molecule has no electrical dipole. Metallic bonding tends to involve close-packed centrosymmetric structures with a high number of nearest neighbours. Polyhedra containing inversion centers are known as centrosymmetric, while those without are noncentrosymmetric. At room temperature, it is a centrosymmetric paraelectric material with a perovskite structure. Of these thirty-two point groups, eleven are centrosymmetric.