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VOLUME 95 | ISSUE 3 | PAGE 179 Universal crossover of liquid dynamics in supercritical region V. V. Brazhkin, Yu. D. Fomin, A. G. Lyapin, V. N. Ryzhov, K. Trachenko× Institute for High Pressure Physics, 142190 Troitsk, Russia ×South East Physics Network and School of Physics, Queen Mary University of London, E1 4NS London, UK Abstract We demonstrate that all liquids in supercritical region may exist in two qualitatively different states: solid-like and gas-like. Solid-like to gas-like crossover corresponds to the condition , where τ is liquid relaxation time and τ0 is the minimal period of transverse waves. This condition corresponds to the loss of shear stiffness of a liquid at all frequencies and defines a new narrow crossover zone on the phase diagram. We show that the intersection of this zone corresponds to the disappearance of high-frequency sound, qualitative changes of diffusion and viscous flow, increase of particle thermal speed to half of the speed of sound and reduction of the constant volume specific heat to 2k B per particle. The new crossover is universal: it separates two liquid states at arbitrarily high pressure and temperature, and even exists in systems where liquid - gas transition and the critical point are absent overall. Download PS file (GZipped, 472.3K)  |  Download PDF file (540.4K)