The structural and dynamical liquid-glass transition for metallic sodium

Abstract

The authors perform a molecular-dynamics simulation for the liquid metal sodium to study the glass transition temperature. Using the same set of liquid to glass structure factors, this is done (a) structurally by calculating the Wendt-Abraham parameter and (b) dynamically by solving the non-linear integral equation embodied in the mode-coupling theory. The glass transition temperature obtained from the former is distinctly lower than that from the latter. In an attempt to explain such a difference in the glass transition temperature, the authors draw attention to some works on shear viscosity coefficients and analyse the latter results in light of the basic hypothesis of the mode-coupling formulation. It appears that the glass transition point obtained in the context of mode-coupling theory for metallic sodium is reasonably predicted, and that the Wendt-Abraham glass transition point, determined directly from the structure data, seems numerically closer to the calorimetric glass transition temperature. Also, the authors compare the metallic non-ergodicity form factor obtained from the molecular-dynamics simulation with the corresponding asymptotic formula proposed in the mode-coupling theory, and they agree reasonably well with each other. The effect of the pair potential on the non-ergodicity form factor is also discussed briefly for both the hard-sphere and the metallic systems.