Assessment of adiabatic local-density approximation for nonlinear optical properties

Employing a near exact Hylleraas wavefunction we calculate various third-or der nonlinear optical properties for the helium atom within the time-depend ent Kohn-Sham theory. In our calculations we employ the adiabatic local-den sity approximation (ALDA) for the exchange and correlation kernels f(xc) an d g(xc), and compare the numbers obtained by us with the available accurate theoretical as well as experimental results. Our results demonstrate the a ccuracy of ALDA for the calculation of nonlinear optical properties of many electron systems.