Summary of the Wigner-Racah algebra of non-simply-reducible point groups with non-ambivalent classes.- Representations induced by polyhedral edges.- Bicentric matrices.- The matrix elements of s.-a. molecular orbitals.- Polyhedral coefficients referring to edges.- Triangular coefficients.- Triangular invariants.- Symmetry-adapted geminals and densities.- Pseudo-tetrahedral coefficients.- Two-particle interaction.- Complete bases of irreducible representations.- Transformation properties and structure of the multi-centre integrals.- Multi-centre integrals and molecular symmetry.- Ab initio determination of the polycentric invariants.- Wolfsberg-Helmholtz and Mulliken approximations.- Floating orbitals.- Overlap- and structural matrices, orthonormalization.- Many-electron systems.- Sketch of the VB picture.- Prospect of crystals.- Case study: Tetrahedral structures.- Case study: Matrix elements.
