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Glassy Dynamics of Confined Fluids

K. G. Ayappa, Department of Chemical Engineering, Indian Institute of Science, Bangalore, India and S. H. Krishnan, Chemical Engineering, Indian Institute of Science, Bangalore, India.

Molecular dynamic simulations of soft-sphere fluids confined in slit pores

reveals that a single component fluid can undergo glass-like dynamics due to confinement.

The self intermediate scattering function, of the confined fluid

exhibits a two step relaxation at moderate temperatures and follows

the time-temperature superposition principle observed in bulk glass formers.

The self-diffusivity and relaxation times of the confined fluid are found to follow scalings

predicted by mode coupling theories developed for bulk glass formers.

The system exhibits a crossover temperature which is above the glass transition temperature.

At lower temperatures, signatures of additional relaxation processes are observed in the various

dynamical quantities with the self-intermediate scattering function relaxing in three steps.

The temperature dependence of the self-diffusivity can be accurately expressed

by the Vogel-Fulcher-Tammann equation and the fluid can be classified as

a fragile glass former based on the fragility index. Simulations are carried out for

pore spacings that can accommodate one to four fluid layers and the influence of the

confining surface (structured or smooth) on the glassy dynamics is explored.