Eur. Phys. J. E (2018) 41: 90
https://doi.org/10.1140/epje/i2018-11702-0

Regular Article

Power law relationship between diffusion coefficients in multi-component glass forming liquids

¹ Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur Campus, 560064, Bengaluru, India
² Tata Institute of Fundamental Research, 500107, Hyderabad, Ranga Reddy District, India
³ Department of Fundamental Engineering, Institute of Industrial Science, The University of Tokyo, Komaba 4-6-1, 153-8505, Meguro-ku, Tokyo, Japan

^* e-mail: sastry@jncasr.ac.in

Received: 23 May 2018
Accepted: 13 July 2018
Published online: 8 August 2018

Abstract

The slow down of dynamics in glass forming liquids as the glass transition is approached has been characterised through the Adam-Gibbs relation, which relates relaxation time scales to the configurational entropy. The Adam-Gibbs relation cannot apply simultaneously to all relaxation times scales unless they are coupled, and exhibit closely related temperature dependences. The breakdown of the Stokes-Einstein relation presents an interesting situation to the contrary, and in analysing it, it has recently been shown that the Adam-Gibbs relation applies to diffusion coefficients rather than to viscosity or structural relaxation times related to the decay of density fluctuations. However, for multi-component liquids --the typical cases considered in computer simulations, metallic glass formers, etc.-- such a statement raises the question of which diffusion coefficient is described by the Adam-Gibbs relation. All diffusion coefficients can be consistently described by the Adam-Gibbs relation if they bear a power law relationship with each other. Remarkably, we find that for a wide range of glass formers, and for a wide range of temperatures spanning the normal and the slow relaxation regimes, such a relationship holds. We briefly discuss possible rationalisations of the observed behaviour.