1. On the physical mechanisms underlying single molecule dynamics in simple liquids.
- Author
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Keanini, Russell G., Dahlberg, Jerry, and Tkacik, Peter T.
- Subjects
- *
SINGLE molecules , *LIQUIDS , *ELECTRON cloud effect , *SELF-diffusion (Solid state physics) , *PHONONS - 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. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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