Method of successive approximations for many - electron wave functions

Assuming that there exists a correspondence between the methods of the superposition of configurations and linked-cluster perturbation-theory expansions, a method of successive approximations was used to generate the coefficients of the superposition-of-configurations expansion and the correlation energy of a many-electron wave function. The algorithm was applied to the ground state of Be. Using an excited $s$, $p$, $d$ orbital basis set calculated in the $V^N$ potential, and estimating the truncation error of the remaining pair-correlation energies of the partial-wave expansion, a correlation energy of -0.09312 a.u. was obtained.