A black-box self-consistent field convergence algorithm: One step closer

A direct inversion iterative subspace version of the relaxed constraint algorithm is a convergence acceleration technique for the solution of the self consistent field (SCF) equations found in the Hartree-Fock method and Kohn-Sham-based density functional theory (KS-DFT). EDIIS is able to bring the density matrix from any initial guess to a solution region, the DIIS method is faster when the density matrix is close to convergence. EDIIS can detect the presence and determine the value of fractional occupations in KS-DFT.