  Some experiments have witnessed increasing decoupling of viscosity from the
translational self-diffusion of supercooled water with decreasing temperature.
While theory and computer simulation studies indicated the jump translation of
the molecules as a probable origin of the above decoupling, a precise
quantitative estimation is still lacking. Through a molecular dynamics (MD)
simulation study, along with careful consideration of translational jump
motion, we have found the most definite proof of increasing relevance of
translational jump diffusion in the above decoupling phenomena. By separating
out the jump-only diffusion contribution from the overall diffusion of the
water, we obtain the residual diffusion coefficient, which remains strongly
coupled with the viscosity of the medium at the whole temperature range,
including supercooled regime. These new findings can help to elucidate many
experimental studies featuring molecular transport properties, where strong
diffusion-viscosity decoupling comes into the picture.
