Simulated disordered-to-ordered phase transition of nonadecane

Nonadecane, normal alkane C19H40, has an orientationally disordered phase (rotator phase) between the melting point (305 K) and the transition temperature (293 K). The phase transition from the disordered phase to the ordered phase during the cooling process beyond the transition temperature was simulated based on the rate equation focusing on the state of molecules rotating or fixed. An experimental time profile curve of the disordered-ordered phase transition progression obtained by terahertz spectroscopy was reproduced successfully, allowing visualization of the transition and the formation of orientational domain structures in computer simulations.