  We investigate crystal nucleation in supersaturated colloid suspensions using
enhanced molecular dynamics simulations augmented with machine learning
techniques. The simulations reveal that crystallization in the model colloidal
system studied here, with particles interacting through a repulsive screened
Coulomb Yukawa potential, proceeds from vapor to dense liquid droplet to
crystalline phases across multiple high barriers. Employing a one-dimensional
reaction coordinate derived from the State Predictive Information Bottleneck
framework, our simulations capture backand-forth phase transitions across
multiple barriers effectively in biased metadynamics simulations. We obtain
relative free energy differences between different phases and also quantify the
roles of different molecular level features in driving the phase changes.
