br Conclusion The Hartree Fock approach was used for

Conclusion The Hartree–Fock approach was used for finding wave functions and single-electron energies of the sodium liver x receptor in the ground and the excited states. The photoionization amplitudes and the photoabsorption cross-sections for this atom were computed through RPAE which explains the experimentally observed autoionization resonance peaks emerging. The polarization corrections necessary for refining the energies and the wave functions of the ground and the excited states were taken into account by various methods, in particular, by the effective static polarization potential model and by the model using the dynamic polarization potential. Comparing the computed and the experimental data proves that it is necessary to take into account the electron–electron correlations in order to qualitatively describe the optical properties of the atoms; it is also useful to take into account the polarization corrections when refining the photoabsorption cross-sections and the ground state energies. In particular, introducing the dynamic polarization potential allowed to significantly improve the agreement between the locations of the autoionization resonance peaks and the experimental data; however, using this method to refine the photoabsorption cross-sections only proved justified for the case of low energies. Possibly, using a relativistic basis may improve the agreement between the computed and the experimental data in the high-energy range. In order to further refine the positions of the autoionization resonance peaks, dendrites is necessary to go beyond the Hartree–Fock approach, in particular, by using the multi-configuration Hartree–Fock approximation and its relativistic generalization. The RPAE method can be applied not only to describing atoms, but also molecules, clusters, and other nanostructures [14–17].