  We calculate ground-state energies and densities of a helium atom confined in
an impenetrable spherical box within density functional theory. These
calculations are performed by variationally solving Kohn-Sham equation with the
ground-state orbital expanded in terms of Slater-type orbitals. Using the
ground-state densities we then calculate static linear polarizability and
nonlinear hyperpolarizability and study their variation with the radius of
confinement. We find that polarizability decreases monotonically with
decreasing confinement radius and the hyperpolarizability not only decreases
but also undergoes a change in sign in the strong confinement regime.
