Testing the validity of Adam–Gibbs equation

Abstract

The Adam–Gibbs (AG) equation may be one of the most influential models in the study of α-relaxation. In this paper, we derived mathematical relationships governing changes in the potential barrier and configurational entropy from a series of nonlinearly scaled potential energy landscapes. By integrating these relationships with molecular dynamics simulations, we revisited the renowned AG model, which establishes a direct correlation between the α-relaxation time, configurational entropy, and potential barrier. Our findings confirm that the AG model effectively depicts the temperature dependence of the α-relaxation time. Additionally, we reassessed other widely used models for α-relaxation, including the Vogel–Fulcher–Tammann model, the shoving model, the Mauro–Yue–Ellison–Gupta–Allan model, and various quadratic-form models, to evaluate their applicability under varying potential barriers. Our results indicate that the potential barrier plays a critical role in these relaxation models. These models perform well when the average potential barrier is high. However, discrepancies arise when the average potential barrier decreases. This research provides an in-depth analysis of α-relaxation, offering new insights into the dynamics of supercooled liquids.