EN
Racah-Wigner type of calculus is adapted to the system of two free electrons in a cubic box, confined to a single star p00 of quasimomentum. Various coupling schemes (LS-like, jj-like, and transitive) have been reviewed in analogy to the case of a free atom. Racah recoupling matrices are calculated explicitly, and their quantum-mechanical meaning is exposed in terms of octahedral multipoles.