Second-order self-consistent field algorithms: from classical to quantum nuclei

Abstract

This work presents a general framework for deriving exact and approximate Newton self-consistent field (SCF) orbital optimization algorithms by leveraging concepts borrowed from differential geometry. Within this framework, we extend the augmented Roothaan--Hall (ARH) algorithm to unrestricted electronic and nuclear-electronic calculations. We demonstrate that ARH yields an excellent compromise between stability and computational cost for SCF problems that are hard to converge with conventional first-order optimization strategies. In the electronic case, we show that ARH overcomes the slow convergence of orbitals in strongly-correlated molecules with the example of several iron-sulfur clusters. For nuclear-electronic calculations, ARH significantly enhances the convergence already for small molecules, as demonstrated for a series of protonated water clusters.

40 pages, 4 figures, 3 tables

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Cited by in corpus (4)

• OpenOrbitalOptimizer -- a reusable open source library for self-consistent field calculations
• Symmetry-Projected Nuclear-Electronic Hartree-Fock: Eliminating Rotational Energy Contamination
• Reaching precise proton affinities in non-Born-Oppenheimer calculations
• A Reusable Library for Second-Order Orbital Optimization Using the Trust Region Method