Convergence of gradient-based algorithms for the Hartree-Fock equations
Provides first complete convergence proofs for key algorithms in quantum chemistry, addressing a long-standing gap for practitioners.
The paper proves convergence of gradient-based algorithms (natural gradient, Roothaan, Level-Shifting) for Hartree-Fock equations using Lojasiewicz inequality, providing convergence rate estimates and numerical validation.
The numerical solution of the Hartree-Fock equations is a central problem in quantum chemistry for which numerous algorithms exist. Attempts to justify these algorithms mathematically have been made, notably in by Cances and Le Bris in 2000, but, to our knowledge, no complete convergence proof has been published. In this paper, we prove the convergence of a natural gradient algorithm, using a gradient inequality for analytic functionals due to Lojasiewicz. Then, expanding upon the analysis of Cances and Le Bris, we prove convergence results for the Roothaan and Level-Shifting algorithms. In each case, our method of proof provides estimates on the convergence rate. We compare these with numerical results for the algorithms studied.