Improved convergence of open-shell SCF calculations
James E. Grabenstetter, Friedrich Grein · Molecular Physics · 1976
It is shown that the level-shifting technique of Guest and Saunders for improving convergence of open-shell SCF iterations can also be applied to the double-matrix formalism of Roothaan and its extension by Huzinaga. Test cases include the lowest 2Σ+ state of PO and a double open-shell 2Σ+ configuration of NS.