The Stokes–Einstein–Debye(SED) relation in TIP5P water is tested with the original formula and its variants within the temperature range 240–390 K. The results indicate that although the variants explicitly break d...The Stokes–Einstein–Debye(SED) relation in TIP5P water is tested with the original formula and its variants within the temperature range 240–390 K. The results indicate that although the variants explicitly break down, the original SED relation is almost valid. Compared with the Stokes–Einstein relation, no explicit decoupling is observed in translational and rotational motion. Variation of the effective hydrodynamic radius is critical to testing the validity of the SED relation.展开更多
Fractional Stokes–Einstein relation described by D ～（τ/T）~ξ is observed in supercooled water, where D is the diffusion constant, τ the structural relaxation time, T the temperature, and the exponent ξ =τ^（-1...Fractional Stokes–Einstein relation described by D ～（τ/T）~ξ is observed in supercooled water, where D is the diffusion constant, τ the structural relaxation time, T the temperature, and the exponent ξ =τ^（-1）. In this work, the Stokes–Einstein relation in TIP5 P water is examined at high temperatures within 400 K–800 K. Our results indicate that the fractional Stokes–Einstein relation is explicitly existent in TIP5P water at high temperatures, demonstrated by the two usually adopted variants of the Stokes–Einstein relation, D ～τ^（-1）τand D ～ T/τ, as well as by D ～ T/η, where η is the shear viscosity. Both D ～τ^（-1）τand D ～ T/τ are crossed at temperature Tx= 510 K. The D ～τ^（-1）τis in a fractional form as D ～ τ ξwith ξ =-2.09 for T ≤ Txand otherwise ξ =τ^（-1）.25. The D ～ T/τ is valid with ξ =τ^（-1）.01 for T ≤ Txbut in a fractional form for T Tx. The Stokes–Einstein relation D ～ T/η is satisfied below Tx = 620 K but in a fractional form above Tx. We propose that the breakdown of D ～ T/η may result from the system entering into the super critical region, the fractional forms of D ～τ^（-1）τand D ～ T/τ are due to the disruption of the hydration shell and the local tetrahedral structure as well as the increase of the shear viscosity.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 12104502)the Natural Science Foundation of Sichuan Province (Grant No. 2023YFG0308)the Fundamental Research Funds for the Central Universities (Grant No. 24CAFUC03057)。
文摘The Stokes–Einstein–Debye(SED) relation in TIP5P water is tested with the original formula and its variants within the temperature range 240–390 K. The results indicate that although the variants explicitly break down, the original SED relation is almost valid. Compared with the Stokes–Einstein relation, no explicit decoupling is observed in translational and rotational motion. Variation of the effective hydrodynamic radius is critical to testing the validity of the SED relation.
基金supported by the National Natural Science Foundation of China(Grant No.2153200)the China Postdoctoral Science Foundation(Grant No.2016M602712)
文摘Fractional Stokes–Einstein relation described by D ～（τ/T）~ξ is observed in supercooled water, where D is the diffusion constant, τ the structural relaxation time, T the temperature, and the exponent ξ =τ^（-1）. In this work, the Stokes–Einstein relation in TIP5 P water is examined at high temperatures within 400 K–800 K. Our results indicate that the fractional Stokes–Einstein relation is explicitly existent in TIP5P water at high temperatures, demonstrated by the two usually adopted variants of the Stokes–Einstein relation, D ～τ^（-1）τand D ～ T/τ, as well as by D ～ T/η, where η is the shear viscosity. Both D ～τ^（-1）τand D ～ T/τ are crossed at temperature Tx= 510 K. The D ～τ^（-1）τis in a fractional form as D ～ τ ξwith ξ =-2.09 for T ≤ Txand otherwise ξ =τ^（-1）.25. The D ～ T/τ is valid with ξ =τ^（-1）.01 for T ≤ Txbut in a fractional form for T Tx. The Stokes–Einstein relation D ～ T/η is satisfied below Tx = 620 K but in a fractional form above Tx. We propose that the breakdown of D ～ T/η may result from the system entering into the super critical region, the fractional forms of D ～τ^（-1）τand D ～ T/τ are due to the disruption of the hydration shell and the local tetrahedral structure as well as the increase of the shear viscosity.
