Photoionization of molecular endohedrals

We calculate the photoionization cross section of a molecular endohedral that denote as M@C$_{\text{N}}$. We limit ourselves to diatomic molecules. The consideration is much more complex than for atomic endohedrals because the system even for almost spherical C$_{\text{N}}$ has only cylindrical instead of spherical symmetry. On the other hand, M@C$_{\text{N}}$ is more interesting since the interelectron interaction in molecules is relatively stronger than in similar atoms. We present here results of calculations of molecular hydrogen H$_2$ stuffed inside almost spherical fullerene C$_{60}$-H$_2$@C$_{60}$. For comparison, we perform calculations also for atomic endohedral He@C$_{60}$. The results are obtained both in the single-electron Hartree-Fock approximation and with account of multi-electron correlations in the frame of so-called random phase approximation with exchange. The presence of the fullerenes shell results in prominent oscillations in the endohedrals photoionization cross section. The role of interelectron correlations becomes clear by comparing Hartree-Fock and random phase approximation with exchange results for H$_2$@C$_{60}$ and He@C$_{60}$ on the one side with that for H$_2$ and He, on the other.