Excess Entropy, Diffusion Coefficient, Viscosity Coefficient and Surface Tension of Liquid Simple Metals from Diffraction Data

抄録

In this paper we will provide a prescription for evaluating properties of liquid metals from measured diffraction data. When a liquid metal structure factor is of hard-sphere form, there is a correlation between structure factor and entropy. This is investigated for liquid alkali, noble and typical polyvalent metals. First of all, we calculate the pair and triplet correlation entropies (S⁽²⁾ and S⁽³⁾) from the measured diffraction data. To evaluate the triplet correlation entropy S⁽³⁾, we do not use the superposition approximation of Kirkwood. Next, assuming that the excess entropy (i.e., ion configurational entropy) S_E is given as S⁽²⁾+S⁽³⁾+S^(x), where S^(x) denotes an entropy contribution arising from the four-body and higher-order terms of correlations, we calculate the self-diffusion coefficient D based on Dzugutov’s scaling law. By means of D, we estimate the viscosity coefficient η and the surface tension γ for these liquid metals using the Stokes-Einstein relation, the Born-Green equation and Fowler’s formula for the surface tension. We can find there exists a clear relationship between S_E, D, η and γ. Predicted values of D, η and γ are reasonable in size in comparison with the available experimental data.