Fan Jingcun, Ly Nguyen, Ihme Matthias
Department of Mechanical Engineering, <a href="https://ror.org/00f54p054">Stanford University</a>, Stanford, California 94305, USA.
Department of Photon Science, <a href="https://ror.org/05gzmn429">SLAC National Accelerator Laboratory</a>, Menlo Park, California 94025, USA.
Phys Rev Lett. 2024 Dec 13;133(24):248001. doi: 10.1103/PhysRevLett.133.248001.
Microstructural heterogeneities arising from molecular clusters directly affect the nonlinear thermodynamic properties of supercritical fluids. We present a physical model to elucidate the relation between energy exchange and heterogeneous cluster dynamics during the transition from liquidlike to gaslike conditions. By analyzing molecular-dynamics data and employing physical principles, the model considers contributions from three key processes, namely, changing cluster density, cluster separation, and transfer of molecules between clusters. We show that the proposed model is consistent with the energetics at subcritical conditions and can be used to explain the nonlinear behavior of thermodynamic response functions, including the peak in the isobaric heat capacity.
