Van Vleck paramagnetism

Van Vleck paramagnetism is a type of paramagnetism associated with materials where unpaired electrons are present in orbitals with a specific symmetry, usually involving d or f orbitals. Unlike typical paramagnetism, where unpaired electrons in atomic orbitals contribute to magnetism primarily due to the alignment of their spins in an external magnetic field, Van Vleck paramagnetism arises from a more complex interaction involving the orbital angular momentum of the electrons.