Visualization of two-body electron densities and wave functions of magnetic molecules

Visualization methods of two-electron wave functions, electron–electron correlation plot, proposed previously are developed for magnetic molecules. This method can provide intuitive understanding of the two-body wave function and is a useful tool to compare characteristics of various approximation methods for many-body problems such as restricted Hartree–Fock (RHF), unrestricted Hartree–Fock (UHF), (GHF), and configuration interaction (CI). Our visualization method is fully explained on the basis of the two-body density matrix. Applications of these methods are performed for trans-butadiene and trimethylene methane, which are typical examples of nonmagnetic and magnetic organic molecules, respectively.