0 Frequency dependent hyperpolarizabilities of atoms ; calculations using density - functional theory

Using the orbitals generated by the van Leeuwen-Baerends potential [Phys. Rev. A 49, 2421 (1994)], we calculate frequency-dependent response properties of the noble gas atoms of helium, neon and argon and the alkaline earth atoms of berrylium and magnisium, with particular emphasis on their nonlinear polarizabilities. For this, we employ the time-dependent Kohn-Sham formalism with the adiabatic local-density approximation (ALDA) for the exchange and correlation. We show that the results thus obtained for frequencydependent polarizabilities (both linear and nonlinear) of the inert gas atoms are highly accurate. On the other hand, polarizabilities of the alkaline earths are not given with the same degeree of accuracy. In light of this, we make an assessment of ALDA for obtaining linear and nonlinear response properties by employing time-dependent density-functional theory.