Constrained nuclear-electronic orbital second-order Moller-Plesset perturbation theory

Gabrielle B. Tucker; Kurt R. Brorsen

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arXiv · 2602.10267

Constrained nuclear-electronic orbital second-order Moller-Plesset perturbation theory

Gabrielle B. Tucker·Kurt R. Brorsen

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Abstract

A multicomponent second-order Møller-Plesset perturbation theory (MP2) method is derived and implemented within the constrained nuclear-electronic orbital (CNEO) framework from a multicomponent generalization of the Hylleraas functional. The CNEO-MP2 method includes electronic-nuclear and nuclear correlation in the calculation of vibrationally averaged molecular properties. Nuclear quantum effects like vibrational averaging, isotopic effects, and zero-point energy can be captured in a single calculation or geometry optimization with CNEO-MP2, eliminating the need to perform costly subsequent calculations to determine higher order force constants as required with many existing methods used to determine vibrational effects upon molecular properties. The CNEO-MP2 method is benchmarked on a test set of diatomic and small polyatomic molecules and ions. Herein, we present internuclear distances, bond angles, potential energy surfaces, and vibrational frequencies calculated with the CNEO-MP2 method to demonstrate that it correctly captures the effects of nuclear vibrational motion upon molecular properties.

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Gabrielle B. Tucker, Kurt R. Brorsen. 2026-04-27. Constrained nuclear-electronic orbital second-order Moller-Plesset perturbation theory. https://arxiv.org/abs/2602.10267

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