Understanding the Cavity Born-Oppenheimer Approximation

Fuente: arXiv
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Auteurs principaux: Fiechter, Marit R., Richardson, Jeremy O.
Format: Preprint
Publié: 2024
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author Fiechter, Marit R.
Richardson, Jeremy O.
author_facet Fiechter, Marit R.
Richardson, Jeremy O.
contents Experiments have demonstrated that vibrational strong coupling between molecular vibrations and light modes can significantly change molecular properties, such as ground-state reactivity. Theoretical studies towards the origin of this exciting observation can roughly be divided in two categories, with studies based on Hamiltonians that simply couple a molecule to a cavity mode via its ground-state dipole moment on the one hand, and on the other hand ab initio calculations that self-consistently include the effect of the cavity mode on the electronic ground state within the cavity Born-Oppenheimer (CBO) approximation; these approaches are not equivalent. The CBO approach is more rigorous, but unfortunately it requires the rewriting of electronic-structure code, and gives little physical insight. In this work, we exploit the relation between the two approaches and demonstrate on a real molecule (hydrogen fluoride) that for realistic coupling strengths, we can recover CBO energies and spectra to high accuracy using only out-of-cavity quantities from standard electronic-structure calculations. In doing so, we discover what the physical effects underlying the CBO results are. Our methodology can aid in incorporating more, possibly important features in models, play a pivotal role in demystifying CBO results and provide a practical and efficient alternative to full CBO calculations.
format Preprint
id arxiv_https___arxiv_org_abs_2401_03532
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Understanding the Cavity Born-Oppenheimer Approximation
Fiechter, Marit R.
Richardson, Jeremy O.
Chemical Physics
Quantum Physics
Experiments have demonstrated that vibrational strong coupling between molecular vibrations and light modes can significantly change molecular properties, such as ground-state reactivity. Theoretical studies towards the origin of this exciting observation can roughly be divided in two categories, with studies based on Hamiltonians that simply couple a molecule to a cavity mode via its ground-state dipole moment on the one hand, and on the other hand ab initio calculations that self-consistently include the effect of the cavity mode on the electronic ground state within the cavity Born-Oppenheimer (CBO) approximation; these approaches are not equivalent. The CBO approach is more rigorous, but unfortunately it requires the rewriting of electronic-structure code, and gives little physical insight. In this work, we exploit the relation between the two approaches and demonstrate on a real molecule (hydrogen fluoride) that for realistic coupling strengths, we can recover CBO energies and spectra to high accuracy using only out-of-cavity quantities from standard electronic-structure calculations. In doing so, we discover what the physical effects underlying the CBO results are. Our methodology can aid in incorporating more, possibly important features in models, play a pivotal role in demystifying CBO results and provide a practical and efficient alternative to full CBO calculations.
title Understanding the Cavity Born-Oppenheimer Approximation
topic Chemical Physics
Quantum Physics
url https://arxiv.org/abs/2401.03532