Linear density response function within the time-dependent exact-exchange approximation

We have calculated the frequency-dependent exact-exchange (EXX) kernel of time-dependent (TD) density-functional theory employing our recently proposed computational method based on cubic splines. With this kernel we have calculated the linear density response function and obtained static polarizabilites, van der Waals coefficients, and correlation energies for all spherical spin-compensated atoms up to argon. Some discrete excitation energies have also been calculated for Be and Ne. As might be expected, the results of the TDEXX approximation are close to those of TD Hartree-Fock theory. In addition, correlation energies obtained by integrating over the strength of the Coulomb interaction turn out to be highly accurate.