Sj. Vanenk et al., CALCULATION OF CHI((3)) IN HE INCLUDING CONFIGURATION-INTERACTION FORXUV PHOTONS, Zeitschrift fur Physik. D, Atoms, molecules and clusters, 37(3), 1996, pp. 211-217
We calculate the third-order susceptibility in He for photon energies
from 19.5 eV to 24.5 eV in a configuration-interaction calculation, an
d discuss the role of autoionizing states as a means of enhancing harm
onic generation.