Breakdown of the Stokes-Einstein relation in supercooled liquids
AuthorDimitrov, Ventzislav Ivanov
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CitationDimitrov, V. I. (2004). Breakdown of the Stokes-Einstein relation in supercooled liquids. Journal of Metastable and Nanocrystalline Materials, 20-21, 541-545. doi:10.4028/www.scientific.net/JMNM.20-21.541
Breakdown of the Einstein-Stokes relation in undercooled liquids is one of the unsolved problems in the theory of liquids. The self-diffusion coefficient follows the temperature dependence of the Einstein-Stokes equation D = kT / 6pietar at high temperatures but only down to approximately 1.2T(g) (T-g - glass-temperature). Below 1.2T(g) the temperature behavior of the diffusion coefficient is weaker than 1/eta. In the present study we show that this is a consequence of increasing correlations in the Brownian motion of the constituting particles of the liquid. We derive a relation, which includes the Einstein-Stokes equation as a limiting case for high temperatures.