Structure And Dynamics Of Hhe3+: The Emergence Of Large-scale Nuclear Delocalization

Simkó, Irén

Permalink

https://hdl.handle.net/2142/116716 Copy

Description

Title

Structure And Dynamics Of Hhe3+: The Emergence Of Large-scale Nuclear Delocalization

Author(s)

Simkó, Irén

Contributor(s)

• Schlemmer, Stephan
• Asvany, Oskar
• Marx, Dominik
• Schran, Christoph
• Brieuc, Fabien
• Császár, Attila
• Fábri, Csaba

Issue Date

2022-06-23

Keyword(s)

Structure determination

Abstract

The HHe$_3^+$ cation is a model system for solvated triatomic molecules, which consists of a (quasi)linear HHe$_2^+$ core (chromophore) and a weakly-bound solvating He.\footnote{\textit{Mol. Phys.} 2019, 117, 9-12, 1559-1583; \textit{J. Phys. Chem. Lett.} 2019, 10, 5325-5330; \textit{Phys. Chem. Chem. Phys.} 2020, 22, 22885-22888} The equilibrium structure is T-shaped, but the ``quantum'' structure is very different, showing large-scale nuclear delocalization. In order to study the structure and dynamics of HHe$_3^+$ we performed path-integral molecular dynamics and variational nuclear-motion computations,\footnote{\textit{J. Chem. Phys.} 2009, 130, 134112.; \textit{J Chem. Phys.} 2011, 134, 074105.; \textit{J. Chem. Phys.} 2017, 147, 134101.} based on a new, highly accurate, neural-network potential-energy surface.\footnote{\textit{Angew. Chem. Int. Ed.} 2017, 56, 12828; \textit{J. Chem. Theo. Comp.} 2020, 16, 88.; https://www.theochem.rub.de/go/rubnnet4md.html} We tested the new potential on the HHe$_2^+$ cation. The computed rovibrational transitions have excellent agreement with experimental data, showing the high quality of the potential. As to the HHe$_3^+$, we determined the vibrational states below and above the dissociation limit, corresponding to the solvating He and the chromophore, respectively. The computed chromophore vibrational frequencies have good agreement with the experimental results. Note that, the frequencies of the chromophore vibrations are significantly shifted compared to that of the HHe$_2^+$, because the intermolecular bond is relatively strong. In order to investigate the ``quantum'' structure, we computed and plotted the nuclear density, which shows the spatial distribution of solvating He with respect to the chromophore. The nuclear density was obtained from path integral molecular dynamics computations and the vibrational wave functions from the nuclear-motion computation. The plots reveal that the true shape of the complex is completely different from the equilibrium structure: the solvating He is fully delocalized, forming a torus around the central proton even in the vibrational ground state. Delocalization is observed for each state, and its exact pattern reflects the type of vibrational excitation.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116716&&

DOI

https://doi.org/10.15278/isms.2022.RL10

Copyright and License Information

Copyright 2022 held by the authors

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