Date: May 10
SPEAKER: Dr.Takeshi Egami, University of Tennessee, Knoxville, TN
ABSTRACT:Liquids are found everywhere, and are critically important to energy infrastructure; hydro-power, oil, lubrication, just to name a few. And yet we understand so little about the liquid at the atomic level. This is because most of the theoretical tools in condensed matter physics assume lattice periodicity and translational invariance, whereas in the liquid atoms are constantly moving and are arranged in a disordered manner. The absence of translational symmetry has made it so difficult to develop sufficiently powerful and sophisticated theory of liquids, because we have to face the many-body problem head-on. There are also dearth of experimental methods to catch the local dynamics of liquids. But recently we made a breakthrough by successfully obtaining the time-dependent atom-atom correlation function, the so-called Van Hove function, by inelastic x-ray scattering experiment for water , and explained the atomistic origin of viscosity . We also determined the local dynamics of superfluid 4He through the dynamic pair-density function by inelastic neutron scattering . These advances form the basis of a new discipline, “liquid-state-physics”, which is the physics of dynamic aperiodic matter.
 T. Iwashita, B. Wu, W.-R. Chen, S. Tsutsui, A.Q. R. Baron and T. Egami, Science Advances, 3, e1603079 (2017).
 T. Iwashita, D. M. Nicholson and T. Egami, Phys. Rev. Lett., 110, 205504 (2013).
 W. Dmowski, S. O. Diallo, K. Lokshin, G. Ehlers, G. Ferré, J. Boronat and T. Egami, Nature Commun. 8, 15294 (2017).