A program to generate closed basic diagrams for product operators

Operators, referred to here as basic operators, such as Hamiltonian, electromagnetic transition and nuclear transfer, are defined in terms of products of single particle creation and annihilation operators (and their matrix elements). In many physical problems, it is necessary to evaluate the scalar and configuration traces of a product of basic operators. The easiest way to achieve this is to find all the diagrams, i.e., complete contractions among the single particle operators. A digital representation is devised so that a definite order between different diagrams can be established. The algorithm for programming on the computer is made efficient by making all possible attempts, while the diagram is being generated, to recognize the pattern for a diagram to be rejected as a basic one. (Auth.)