On the physical mechanisms underlying single molecule dynamics in simple liquids
Abstract Physical arguments and comparisons with published experimental data suggest that in simple liquids: (i) single-molecule-scale viscous forces are produced by temperature-dependent London dispersion forces, (ii) viscosity decay with increasing temperature reflects electron cloud compression a...
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| Auteurs principaux: | , , |
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| Format: | article |
| Langue: | EN |
| Publié: |
Nature Portfolio
2021
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| Sujets: | |
| Accès en ligne: | https://doaj.org/article/52baabd88c80482d8f5ef4993f5c756f |
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| Résumé: | Abstract Physical arguments and comparisons with published experimental data suggest that in simple liquids: (i) single-molecule-scale viscous forces are produced by temperature-dependent London dispersion forces, (ii) viscosity decay with increasing temperature reflects electron cloud compression and attendant suppression of electron screening, produced by increased nuclear agitation, and (iii) temperature-dependent self-diffusion is driven by a narrow band of phonon frequencies lying at the low-frequency end of the solid-state-like phonon spectrum. The results suggest that collision-induced electron cloud distortion plays a decisive role in single molecule dynamics: (i) electron cloud compression produces short-lived repulsive states and single molecule, self-diffusive hops, while (ii) shear-induced distortion generates viscosity and single-molecule-scale viscous drag. The results provide new insight into nonequilibrium molecular dynamics in nonpolar, nonmetallic liquids. |
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