New Techniques for the Computation of Multiconfiguration Self-Consistent Field (MCSCF) Wavefunctions

New techniques are described for obtaining MCSCF wavefunctions and energies via the expansion method. These include (i) a simple but generalized algorithm for obtaining symmetrized configurations and the corresponding vector-coupling coefficients for diagonal and off-diagonal matrix elements referred to the symmetry species of a diatomic molecule; (ii) a new iterative scheme which leads to a fast convergence of the MCSCF process provided the starting conditions are properly chosen, and (iii) a method to ensure such proper starting conditions in regard to the form of the initial orbitals.