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Fundamental transport properties of liquid para-hydrogen (p-H2), i.e., diffusion coefficients, thermal conductivity, shear viscosity, and bulk viscosity, have been evaluated by means of the path integral centroid molecular dynamics (CMD) calculations. These transport properties have been obtained over the wide temperature range, 14–32 K. Calculated values of the diffusion coefficients and the shear viscosity are in good agreement with the experimental values at all the investigated temperatures. Although a relatively large deviation is found for the thermal conductivity, the calculated values are less than three times the amount of the experimental values at any temperature. On the other hand, the classical molecular dynamics has led all the transport properties to much larger deviation. For the bulk viscosity of liquid p-H2, which was never known from experiments, the present CMD has given a clear temperature dependence. In addition, from the comparison based on the principle of corresponding states, it has been shown that the marked deviation of the transport properties of liquid p-H2 from the feature which is expected from the molecular parameters is due to the quantum effect. [ABSTRACT FROM AUTHOR]

We investigate the nature of cooperative relaxation at the crossover temperature. The relaxation time for a cooperative rearranging region at the crossover temperature is related to the ratio of the entropy and the heat capacity of the supercooled liquid, and the ratio of the glass transition to the crossover temperatures. The lifetime of “elementary” excitations in supercooled liquid is determined by a variational technique. By imposing self-consistency between lifetime of elementary excitations and hopping relaxation time on the potential energy surface, the relaxation time at the crossover temperature is estimated. The predictions are in excellent agreement with available experimental data. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]