  Despite great efforts over the past 50 years, the simulation of water still
presents significant challenges and open questions. At room temperature and
pressure, the collective molecular interactions and dynamics of water molecules
may form local structural arrangements that are non-trivial to classify. Here
we employ a data-driven approach built on Smooth Overlap of Atomic Position
(SOAP) that allow us to compare and classify how widely used classical models
represent liquid water. Macroscopically, the obtained results are rationalized
based on water thermodynamic observables. Microscopically, we directly observed
how transient ice-like ordered environments may dynamically/statistically form
in liquid water, even above the freezing temperature, by comparing the SOAP
spectra for different ice structures with those of the simulated liquid
systems. This confirms recent ab initio-based calculations, but also reveals
how the emergence of ephemeral local ice-like environments in liquid water at
room conditions can be captured by classical water models.
