Effect of initial-state geometric configurations on the nuclear liquid-gas phase transition

Within the framework of an extended quantum molecular dynamics model, we simulated ${}^{40}$Ca + ${}^{16}$O collisions at beam energies ranging from 60 to 150 MeV/nucleon for ${}^{16}$O with different $\alpha$-cluster configurations. Results imply that different $\alpha$-cluster configurations lead to different yields of deuteron, triton, ${}^3$He and ${}^4$He, but not for proton and neutron. We discuss the effect of geometric fluctuations which are presented by double ratios of light nuclei, namely ${\mathcal{O}}_{\text{p-d-t}}$ and ${\mathcal{O}}_{\text{p-d-He}}$. It is found that magnitude hierarchy of geometric fluctuations is chain, kite, square and tetrahedron structure of ${}^{16}$O. ${\mathcal{O}}_{\text{p-d-t}}$ has maximum value around 80 – 100 MeV/nucleon which could be related to liquid-gas phase transition, that is consistent with results from the charge distribution of the heaviest fragments in the collisions.