Pressure effects in supercooled water: comparison between a 2D model of water and experiments for surface water on a protein

摘要: Water's behavior differs from that of normal fluids, having more than sixty anomalies. Simulations and theories propose many these anomalies result the coexistence two liquid phases with different densities. Experiments in bulk water confirm existence local arrangements molecules densities, but, because inevitable freezing at low temperature T, cannot ascertain whether separate into phases. To avoid freezing, new experiments measure dynamics T on surface proteins, finding a crossover non-Arrhenius regime high to is approximately Arrhenius T. Motivated by experiments, Kumar et al (2008 Phys. Rev. Lett. 100, 105701) investigated, Monte Carlo simulations mean field calculations cell model for dimensions (2D), relation dynamic They show orientational correlation time r consequence rearrangement hydrogen bonds predict that: (i) isochronic, i.e. value τ L independent pressure P; (ii) activation energy E A (P) low-T decreases upon increasing (iii) T* which reaches fixed macroscopic τ* ≥ particular, this true also = . Here, we compare predictions recent quasi-elastic neutron scattering (QENS) performed Chu hydrated proteins values P. We find are consistent three predictions.