Distinguishing Liquid from Solid by Atom Transport Coefficient Distribution: Predicting Melting Point of Ionic Liquids as an Example

We define a dynamics parameter, the atom transport coefficient D atom , which is extracted from molecular trajectory using the simple mean square displacement analysis. The D atom of a molecular system has a log‐normal distribution in a homogeneous phase, and the Mode of the log‐normal distribution presents an abrupt change between solid and liquid phase. The D atom can therefore serve as a practical probe for detecting phase transition, which has been validated by simulating melting points for a Lennard‐Jones model and three imidazolium‐based room temperature ionic liquids. Additionally, the molecular dynamics simulations for the melting points are crystal independent and force field non‐restricted. Thus, the presented use of D atom distribution is a new technique for phase transition studies.