Targeting spectroscopic accuracy for dispersion bound systems from ab initio techniques: Translational eigenstates of
K Panchagnula1, D Graf1,2, E R Johnson1,3
1Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.
The Journal of Chemical Physics
|August 2, 2024
Summary
Investigating the Ne@C70 endofullerene system reveals inconsistencies among electronic structure methods in describing its potential energy surface. This highlights the need for experimental data to validate theoretical models for fullerene dynamics.
Area of Science:
- Computational Chemistry
- Quantum Mechanics
- Materials Science
Background:
- Endofullerene systems, like Ne@C70, involve encapsulating atoms within fullerene cages.
- Understanding the atom's motion within the cage is crucial for predicting material properties.
Purpose of the Study:
- To construct and analyze the three-dimensional Potential Energy Surface (PES) for Ne@C70.
- To evaluate the performance and sensitivity of various electronic structure methods for describing the Ne atom's translational motion within C70.
Main Methods:
- Electronic structure calculations using multiple methods (MP2, SCS-MP2, SOS-MP2, RPA@PBE, C(HF)-RPA, B86bPBE-XDM variants).
- Construction of a 3D PES for Ne@C70, accounting for the double well potential due to reduced symmetry compared to C60.
- Diagonalization of the nuclear Hamiltonian using a symmetrized double minimum basis set.
Main Results:
- Significant inconsistencies were found between different electronic structure methods regarding barrier heights, minima positions, and translational energy spectra.
- The widely used Lennard-Jones (LJ) potential energy surface model and its parameters failed to accurately reproduce the calculated PES and eigenstates.
- The choice of electronic structure method impacts the predicted dynamics, with no single method showing clear superiority for Ne@C70.
Conclusions:
- The lack of concordance among theoretical methods suggests limitations in current electronic structure approaches for accurately modeling Ne@C70.
- The simple Lennard-Jones potential may be inadequate for describing the complex interactions within endofullerenes like Ne@C70.
- Further experimental data is essential to validate theoretical predictions and guide the selection of appropriate computational methods.
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