Molecular simulation algorithms generate trajectories of each particle in the system. Each particle represents either a single atom (for the case of all-atom MD simulations) or a collection of atoms (for the case of coarse-grained MD simulations). The relative positions of the different types of particles under different conditions carry the necessary information of the system. With this in mind, the simplest feature we could think of is the number of particles of a certain type around a given center particle within a specified distance from this center particle. We denote this number as nx-y, where x is center particle and y is the particle surrounding this center particle, while the cut-off distance (considered as a hyper parameter) from the center particle used for this calculation is 7 Å (see Fig. ). The biggest molecule in our system is the {N(CH3)3} + functional group of the PMETAC chain, which has a radius of 6 Å. The features that we chose are namely nN-Cl, nN-Ow, nOw-Cl, nCl-Ow , nN-N, nmon-mon [where N, Cl, Ow, and "mon" refer to the nitrogen of the {N(CH3)3 + }, Chloride ion, water-oxygen-atoms, and PMETA monomers (or the carbon atoms of the PMETA monomer)].