What correlation effects are covered by density functional theory

摘要: The electron density distribution ρ(r) generated by a DFT calculation was systematically studied comparison with series of reference densities obtained wavefunction theory (WFT) methods that cover typical correlation effects. As sensitive indicator for effects the dipole moment CO molecule used. analysis reveals LDA and GGA exchange functional already simulate are actually reminiscent pair three-electron covered MP2, MP4, CCSD(T) in WFT. Correlation functionals contract towards bond valence region thus taking negative charge out van der Waals region. It is shown these improvements relevant description interactions. Similar to certain correlated single-determinant WFT methods, BLYP other underestimate ionic terms needed correct polar bonds. This compensated hybrid mixing in...