with positive values indicating concerted motion of the two quasiparticles (Fig. ) and negative values indicating that they avoid each other dynamically (Fig. ). Analysis of correlations between the size of the electron and hole quasiparticles as a function of conjugation length suggests that the semilocal TD-DFT results for (PPV) 20 in Fig. are consistent with quasiparticles avoiding one another, or in other words, more consistent with a CT state than with a bound exciton. Reducing the fraction of Hartree-Fock exchange is tantamount to eliminating electron-hole attraction, or equivalently, to an effectively repulsive interaction between the excited electron and the hole. As a result, TD-DFT using semilocal functionals contains no electron-hole interaction! Semilocal DFT, meaning generalized gradient approximations (GGAs), 1 is thus inherently unable to describe bound excitons. This explains large errors for excitations energies in conjugated π systems that had been observed in previous TD-DFT calculations. The origin of this failure cannot be deduced from the MOs alone, because the anti-diagonal length scales (PR adiag ) are essentially identical for all functionals. Instead, real-space analysis of the transition density (i.e., visualization of electron-hole correlation) is required.