AbstractThe principles of an efficient, fast algorithm for the calculation of diagrams appearing in Green function and many‐body perturbation methods are discussed and timing examples are given. Within the suggested algorithm, the third order‐diagrams required in the Green function approach are evaluated by arranging computations in such a way that the most inner loops contain only simple scalar products and multiplication of vector by scalar operations. The molecular symmetry is taken into account for abelian groups. © 1993 John Wiley&Sons,