  A class of silicon carbide cage clusters with two carbon atoms inside the
silicon cage and with high stabilities are presented. The theoretical formalism
used is Hartree-Fock theory followed by second order many body perturbation
theory to account for correlation effects and geometry optimizations at the
second order perturbation theory level are performed without any symmetry
constraints. The smallest "cage" is found to be a silicon cube with the carbon
dimer inside the cube. Based on the simultaneous criteria of high binding
energy, high vertical ionization potential, high homo-lumo gap, and low
electron affinity, Si_14C_2 with a close fullerene like structure, is predicted
to be a particularly stable cluster both al all-electron and at pseudopotential
level of calculations. The C-C bond lengths and the HOMO-LUMO gaps of the
clusters are both found to oscillate with the cluster size.
