Mean-Squared Energy Difference for Exploring Potential Energy Landscapes of Supercooled Liquids

By extending the concept of diffusion to the potential energy landscapes (PELs), we introduce the meansquared energy difference (MSED) as a novel quantity to investigate the intrinsic properties of supercooled liquids. MSED can provide a clear description of the “energy relaxation” process on a PEL. Through MSED analysis, we have obtained a characteristic time similar to that derived from structure analysis, namely τ_α^*. Further, we establish a connection between MSED and the feature of PELs, providing a concise and quantitative description of PELs. The relaxation behavior of energy has been found to follow a stretched exponential form. As the temperature decreases, the roughness of the accessible PEL changes significantly around a characteristic temperature T_x, which is 20% higher than the glass transition temperature T_g and is comparable to the critical temperature of the mode-coupling theory. More importantly, one of the PEL parameters is closely related to the Adam–Gibbs configurational entropy. The present research, which directly links the PEL to the relaxation process, provides avenues for further research of glasses.