Thursday September 7 at 15.00 Inghe lecture hall, Widerströmska Huset, Tomtebodavägen 18a, KI Campus (NOTE NEW VENUE!) Lars G.M, Pettersson,Department of Physics, AlbaNova University Center, Stockholm University A Two-State Picture of Water and the Funnel of Life

Abstract: I will discuss recent experimental and simulation data of liquid water and the picture of fluctuations between high-density (HDL) and low-density (LDL) liquid this has led to [1,2]. The HDL would be a more close-packed form, favored by entropy and dominates at high temperature. Below about 50°C correlated fluctuations into tetrahedral (LDL) structures, favored by hydrogen-bonding (enthalpy), begin to appear and become increasingly important upon further cooling [3,4]. A coexistence line between the two liquid phases is hypothesized, but it must lie at high pressure and low temperature in the so-called “No-man’s land” where measurements are extremely challenging due to rapid crystallization [5,6]. If such a line exists, it may terminate in a critical point from which a funnel-like region of enhanced fluctuations between the two forms emanates. Since these fluctuations are observed up to ambient conditions we may live in what could be called the “funnel of Life”. In light of this picture I will discuss some of the more important anomalous properties of water.

References:

[1] Anders Nilsson and Lars G.M. Pettersson, The Structural Origin of Anomalous Properties of Liquid Water, Nature Commun. 6, 8998 (2015).

[2] P. Gallo et al., Water: A Tale of Two Liquids, Chem. Rev. 116, 7463-7500 (2016).

[3] L. B. Skinner et al., The Structure of Water Around the Compressibility Minimum, J. Chem. Phys. 141, 214507 (2014).

[4] D. Schlesinger, K.T. Wikfeldt, L.B. Skinner, C.J. Benmore, A. Nilsson and L.G.M. Pettersson, The temperature dependence of intermediate range oxygen-oxygen correlations in liquid water, J. Chem. Phys. 145, 084503 (2016).

[5] J. A. Sellberg et al., Ultrafast X-ray probing of water structure below the homogeneous ice nucleation temperature, Nature 510, 381 (2014)

[6] F. Perakis et al., Diffusive dynamics during the high- to low-density transition in amorphous ices, Proc. Natl. Acad. Sci. 114, 8193 (2017)

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