Mode damping in multiconfigurational Hartree–Fock procedures

Mode damping techniques that allow a controlled ’’walk’’ on the energy hypersurface both within the orbital and the configuration space are introduced. The use of these techniques is particularly crucial in cases where there is strong coupling between the orbital and the configuration space, e.g., the second 1Σ+g state of C2. The mode damping technique allows us to use a set of single configuration Hartree–Fock orbitals as an initial guess of orbitals and then coverge in very few iterations.