  The electronic structure of Ce2 is studied in a valence bond model with two
4f electrons localized at two cerium sites. It is shown that the low-lying
energy spectrum of the simplest cerium chemical bond is determined by
peculiarities of the occupied 4f states. The model allows for an analytical
solution which is discussed along with the numerical analysis. The energy
spectrum is a result of the interplay between the 4f valence bond exchange, the
4f Coulomb repulsion and the spin-orbit coupling. The calculated ground state
is the even \Omega=\Lambda=\Sigma=0 level, the lowest excitations situated at
30 K are the odd \Omega=\Lambda=\Sigma=0 state and the $^{3} 6_5$ doublet
(\Omega=\pm5,\, \Lambda=\pm6,\, \Sigma=\mp1). The calculated magnetic
susceptibility displays different behavior at high and low temperatures. In the
absence of the spin-orbit coupling the ground state is the ${}^3 \Sigma_g^-$
triplet. The results are compared with other many-electron calculations and
experimental data.
