MCSCF calculation of the frequency-dependent hyperpolarizability of the lithium atom

The second electric dipole hyperpolarizability of the lithium atom is calculated using a series of multiconfiguration SCF wave functions with an increasing number of active space orbitals. In agreement with other recent calculations, we find a very large correlation correction to the hyperpolarizability. We analyze the frequency dependence of the dc Kerr hyperpolarizability γ^K(o) = γ (− o o, 0, 0) and observe very significant dispersion effects. © 1996 John Wiley & Sons, Inc.