Recovering Exact Vibrational Energies Within a Phase Space Electronic Structure Framework

Fuente: arXiv
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Autores principales: Wu, Xinchun, Bian, Xuezhi, Rawlinson, Jonathan, Littlejohn, Robert G., Subotnik, Joseph E.
Formato: Preprint
Publicado: 2025
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author Wu, Xinchun
Bian, Xuezhi
Rawlinson, Jonathan
Littlejohn, Robert G.
Subotnik, Joseph E.
author_facet Wu, Xinchun
Bian, Xuezhi
Rawlinson, Jonathan
Littlejohn, Robert G.
Subotnik, Joseph E.
contents In recent years, there has been a push to go beyond Born-Oppenheimer theory and build electronic states from a phase space perspective, i.e. parameterize electronic states by both nuclear position(R) and nuclear momentum(P). Previous empirical studies have demonstrated that such approaches can yield improved single-surface observables, including vibrational energies, electronic momenta, and vibrational circular dichroism spectra. That being said, unlike the case of BO theory, there is no unique phase space electronic Hamiltonian, nor any theory for using phase space eigenvectors (as opposed to BO eigenvectors) so as to recover exact quantum vibrational eigenvalues. As such, one might consider such phase space approaches ad hoc. To that end, here we show how to formally extract exact quantum energies from a coupled nuclear-electronic Hamiltonian using perturbation theory on top of a phase space electronic framework. Thus, while we cannot isolate an "optimal" phase space electronic Hamiltonian, this work does justify a phase space electronic structure approach by offering a rigorous framework for correcting the zeroth order phase space electronic states.
format Preprint
id arxiv_https___arxiv_org_abs_2506_08230
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Recovering Exact Vibrational Energies Within a Phase Space Electronic Structure Framework
Wu, Xinchun
Bian, Xuezhi
Rawlinson, Jonathan
Littlejohn, Robert G.
Subotnik, Joseph E.
Chemical Physics
Quantum Physics
In recent years, there has been a push to go beyond Born-Oppenheimer theory and build electronic states from a phase space perspective, i.e. parameterize electronic states by both nuclear position(R) and nuclear momentum(P). Previous empirical studies have demonstrated that such approaches can yield improved single-surface observables, including vibrational energies, electronic momenta, and vibrational circular dichroism spectra. That being said, unlike the case of BO theory, there is no unique phase space electronic Hamiltonian, nor any theory for using phase space eigenvectors (as opposed to BO eigenvectors) so as to recover exact quantum vibrational eigenvalues. As such, one might consider such phase space approaches ad hoc. To that end, here we show how to formally extract exact quantum energies from a coupled nuclear-electronic Hamiltonian using perturbation theory on top of a phase space electronic framework. Thus, while we cannot isolate an "optimal" phase space electronic Hamiltonian, this work does justify a phase space electronic structure approach by offering a rigorous framework for correcting the zeroth order phase space electronic states.
title Recovering Exact Vibrational Energies Within a Phase Space Electronic Structure Framework
topic Chemical Physics
Quantum Physics
url https://arxiv.org/abs/2506.08230