Effect of Pressure on Translational Diffusion-Viscosity Decoupling in Supercooled Water: Role of Translational Jump motion

 

Vikas Dubey, Snehasis Daschakraborty*

Department of chemistry, Indian Institute of Technology Patna, Bihar.

Email vikas.pch17[at]iitp.ac.in

 

Supercool water is a fascinating medium having several anomalies, found in the experiment. The decrease of viscosity (or an increase of diffusion) with the increase of pressure is one of them.¹ Earlier studies have revealed a strong effect of pressure on the increasing violation of the Stokes-Einstein relation or the gradual decoupling between the diffusivity and the viscosity (or structural relaxation time) of the medium as the system is cooled down. Previous simulation studies² have explained the above observation by connecting the above violation with the widom line the extrapolated line drawn from the second critical point. However, the actual molecular picture for this hypothetical connection is elusive. Recently, we have been able to explain the observed viscosity-diffusion decoupling in supercooled water using a new approach³, which is based on translation jump-diffusion mechanism. The similar methodology has been used to explain the above pressure dependence on the decoupling. This gives us a better understanding of the possible role of translational jump motion of water molecules for the pressure dependence. The results will be discussed in the poster in great detail.

 

Reference:

1-   L. P. Singh, B. Issenmann, and F. Caupin, Proc Natl Acad Sci USA 114, 4312 (2017)

2-   P. Kumar, S. V. Buldyrev, S. R. Becker, P. H. Poole, F. W. Starr, and H. E. Stanley, Proc Natl Acad Sci USA 104, 9575 (2007).

3-   S. Dueby, V. Dubey, S. Daschakraborty, arXiv:1810.03800 (2019).