Hyperpolarizability of the neon atom

The multiconfiguration time-dependent Hartree-Fock method is applied to compute the hyperpolarizabiltiy of the neon atom and its frequency dependence. For the static limit {γ}={γ}(0;0,0,0) we obtain {γ}=86.5 a.u. This value agrees very well with a recent experimental value of 75 a.u. <{γ}<93 a.u. obtained by Shelton and Lu [Phys. Rev. A 37, 3813 (1988)]. The results for the Kerr hyperpolarizability {γ}({ω};0,0,{ω})=γKerr provide an estimate of the dispersion effects. Approximating our results with the formula γ^Kerr=γ(1+AωL²), where for the Kerr effect ωL²=2ω², we find A{}0.50×{}10^-10 cm².