Within the isospin-dependent quantum molecular-dynamics (IQMD) framework, we investigate the multiplicity information entropy $H$ of neutrons, protons, intermediate-mass fragments (IMFs), and all fragments, together with the $\mathrm{\Delta }$-scaling behaviors, in central ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ collisions over an incident energy range of $E=20–350\mathrm{MeV}/\mathrm{nucleon}$. The information entropy of IMFs exhibits a plateau around $E=110$ MeV/nucleon, while that of all fragments shows a pronounced turning point at a similar energy. When considered together with other observables, these features reflect a correlated change in fragment production dynamics in this energy region. In contrast, the $\mathrm{\Delta }$-scaling analysis of the largest fragment charge $Z_{\max }$ does not indicate a transition from $\mathrm{\Delta }=1/2$ to $\mathrm{\Delta }=1$ over the same energy range. However, the charged-fragment multiplicity exhibits distinct $\mathrm{\Delta }$-scaling behaviors in low- $(E=20–80\mathrm{MeV}/\mathrm{nucleon})$ and high-energy $(E=100–350\mathrm{MeV}/\mathrm{nucleon})$ regions. These combined observations suggest that the multiplicity information entropy and the $\mathrm{\Delta }$-scaling behavior of charged fragments consistently reflect a coherent change in the fragmentation dynamics around $E=110$ MeV/nucleon.

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• Liquid-liquid phase transition
• Low & intermediate energy heavy-ion reactions
• Models & methods for nuclear reactions
• Nuclear fragmentation