Investigation of Trapping Positions for Beryllium Atom in C$_{60}$ Fullerene and Electron Densities at$^{ 7}$Be Nucleus.

We are investigating, using first-principles Hartree-Fock Roothaan procedure, the trapping sites for $^{7}$Be atom in C$_{60}$ Fullerene, following broadly the same procedure as in earlier work by our group for trapping of muonium [1]. A number of possible sites, including the center of the C$_{60}$ and various positions near the fullerene surface both outside and inside C$_{60}$ are being studied including the effect of relaxation in the positions of neighboring C atoms. Electron densities at the $^{7}$Be nucleus will be presented for the sites where the binding energy is positive to attempt to understand the observed anomalous electron capture rate compared to other systems where trapped $^{7}$Be atom has been studied [2]. Results of our investigations for$^{ 7}$Be atom in graphite and graphene will also be presented for comparison with $^{7}$Be in C$_{60}$. Possible influence of many-body effects will be discussed. [1] O. Donzelli, T. Briere, T.P. Das, Sol St. Comm. \underline {90 }663(1994), Indian J. Phys. \underline {67 }(Special Issue) 35 (1993) [2] Ohtsuki et al, Phys. Rev. Lett. \underline {93},112501, (2004)