Simultaneous Optimization of Nuclear–Electronic Orbitals

Accurate modeling of important nuclear quantum effects, such as nuclear delocalization, zero-point energy, and tunneling, as well as non-Born–Oppenheimer effects, requires treatment of both nuclei and electrons quantum mechanically. The nuclear–electronic orbital (NEO) method provides an elegant fra...

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Bibliographic Details
Published in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2022-10, Vol.126 (39), p.7033-7039
Main Authors: Liu, Aodong, Chow, Mathew, Wildman, Andrew, Frisch, Michael J., Hammes-Schiffer, Sharon, Li, Xiaosong
Format: Article
Language:English
Subjects:
A: New Tools and Methods in Experiment and Theory
Algorithms
Basis sets
Chemical calculations
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Optimization
Quantum mechanics
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Summary:Accurate modeling of important nuclear quantum effects, such as nuclear delocalization, zero-point energy, and tunneling, as well as non-Born–Oppenheimer effects, requires treatment of both nuclei and electrons quantum mechanically. The nuclear–electronic orbital (NEO) method provides an elegant framework to treat specified nuclei, typically protons, on the same level as the electrons. In conventional electronic structure theory, finding a converged ground state can be a computationally demanding task; converging NEO wavefunctions, due to their coupled electronic and nuclear nature, is even more demanding. Herein, we present an efficient simultaneous optimization method that uses the direct inversion in the iterative subspace method to simultaneously converge wavefunctions for both the electrons and quantum nuclei. Benchmark studies show that the simultaneous optimization method can significantly reduce the computational cost compared to the conventional stepwise method for optimizing NEO wavefunctions for multicomponent systems.
ISSN:1089-5639
1520-5215
DOI:10.1021/acs.jpca.2c05172