The first and second hypersusceptibility of the La@C82 crystal: Effects of disorder

• Using the Hartree–Fock single-excitation configuration interaction (HF-CI) model in conjunction with the local field method, the linear susceptibility tensor, first hypersusceptibility tensor and second hypersusceptibility tensor of the simple cubic (sc) phase of the La@C82 crystal are calculated.
• The HF-CI-type electron–phonon model for the La@C82 crystal is solved with site disorder.
• The calculations show that the intensity fluctuations in the hypersusceptibility spectra of the La@C82 crystal are more than the susceptibility spectra.
• The Coulomb interactions and effects of disorder cause increasing hypersusceptibility tensor.
• Our results show that the optical excitation in the region where the energy is lower than 4 eV has the strongest nonlinear optical absorption bands in the La@C82 crystal.

Using the Hartree–Fock single-excitation configuration interaction (HF-CI) model in conjunction with the local field method, the linear susceptibility tensor, first hypersusceptibility tensor and second hypersusceptibility tensor of the simple cubic (sc) phase of the La@C82 crystal are calculated. The HF-CI-type electron–phonon model for the La@C82 crystal is solved with site disorder. The calculations show that the second hypersusceptibility tensor of the La@C82 crystal is large. The Coulomb interactions and effects of disorder cause increasing hypersusceptibility tensor. Our results show that the optical excitation in the region where the energy is lower than 4 eV has the strongest nonlinear optical absorption bands in the La@C82 crystal.