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Two new flexible-monomer two-body ab initio potential energy surfaces (PESs) for the neon and krypton van der Waals complexes with carbon dioxide were developed, extending our previous work on the Ar–CO2 molecule. The accuracy of the PESs was validated by their agreement with the vibrational spectrum of the rare-gas complexes. The intermolecular and intramolecular vibrational excitation energies were computed at the vibrational self-consistent field and vibrational configuration interaction levels of theory. Overall, the agreement between theory and experiment is excellent throughout the vibrational spectra. The observed slight splitting of the bending modes, resulting from their nondegeneracy in the complexes, is confirmed by our computations, and the results qualitatively agree with the experiment. The splitting increases with increasing polarizability of the rare-gas atom. Additionally, we explain a discrepancy in the mode assignment in the intermolecular region of the neon complex with our VCI character assignment.
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Proton NMR relaxation from molecular dynamics: intramolecular and intermolecular contributions in water and acetonitrile
NMR relaxation rates for protons in liquid water and neat acetonitrile were computed based on ab initio molecular dynamics (aiMD) with forces from Kohn–Sham (KS) theory as well as force-field (FF) based classical dynamics. Intra- and intermolecular dipole–dipole contributions were separated, and nearly quantitative agreement with experiment was obtained for water. Spin-rotation (SR) contributions to the intramolecular relaxation rate in acetonitrile were computed using nuclear SR coupling tensors obtained from KS theory. Their inclusion improved the total computed intramolecular rate to within a factor of two of experiment. Insufficient sampling of rare short-time collision events between neighboring acetonitrile molecules in the simulations is hypothesized as a major source of error in the intermolecular contributions.
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- Award ID(s):
- 1855470
- PAR ID:
- 10162285
- Date Published:
- Journal Name:
- Physical Chemistry Chemical Physics
- Volume:
- 21
- Issue:
- 48
- ISSN:
- 1463-9076
- Page Range / eLocation ID:
- 26621 to 26629
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/c9cp04976b
