Second-Order Self-Consistent Field Algorithms: From Classical to Quantum Nuclei

Robin Feldmann

doi:10.1021/acs.jctc.2c01035

Second-Order Self-Consistent Field Algorithms: From Classical to Quantum Nuclei

2023-01-26

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DOI：10.1021/acs.jctc.2c01035

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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.

Keywords:

MOLECULAR-ORBITAL THEORY

PROTONIC STRUCTURE

SIMULTANEOUS-OPTIMIZATION

BORN-OPPENHEIMER

COUPLED-CLUSTER

AMMONIA

SPECTRUM

METHANE

WATER

Second-Order Self-Consistent Field Algorithms: From Classical to Quantum Nuclei

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