Universal crossover of liquid dynamics in supercritical region

作者：Brazhkin V V^*; Fomin Yu D; Lyapin A G; Ryzhov V N; Trachenko K

来源：JETP Letters, 2012, 95(3): 164-169.

DOI：10.1134/S0021364012030034

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 tau a parts per thousand tau(0), where tau is liquid relaxation time and tau(0) is the minimum 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 in particle thermal speed to half of the speed of sound and reduction of the specific heat at constant volume 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.

• 出版日期2012-4