STRUCTURAL-PROPERTIES OF THE ENDOHEDRAL COMPLEX NA-C60(AT)

We have studied the electronic and structural properties of the so-cal led endohedral complex Na+@C60 which consists of a C60 molecule with a sodium ion trapped inside. Based on the Su-Schrieffer-Heeger (SSH) mo del and the analysis of physical pictures of this kind of complex, we have introduced two reasonable terms into the Hamiltonian to describe the interaction between the ion and the C60 cage. Using the simplex op timization method, we have calculated the lattice distortion and its e ffect on the energy potential curve. Our results show that this effect , which has been neglected by other first-principles calculations, is very large and important. We discuss the physical meaning of our resul ts.