Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/4/eaav7399/DC1

Supplementary Text

Fig. S1. Phase diagram as presented in (*50*).

Fig. S2. Supersaturation as a function of the excess number of particles for liquid critical droplets.

Fig. S3. Initial and final paths for crystallization with a final cluster of 286 molecules using 50 images and a final path using 20 images showing the excess free energy as a function of Euclidean distance along the path (arbitrarily scaled so that the distance between images is equal to one).

Fig. S4. Log of the density for slices of images from the initial guess to the pathway.

Fig. S5. Nucleation pathways for several systems displayed in terms of the free energy along the paths.

Fig. S6. Nucleation pathways for several systems displayed in terms of the number of molecules in the clusters along the paths.

Fig. S7. Excess number of particles in the critical clusters as a function of supersaturation.

Fig. S8. Excess free energies in the critical clusters as a function of supersaturation.

Table S1. Thermodynamic quantities at weak-solution/dense-solution liquid-liquid coexistence.

Table S2. Thermodynamic quantities used in liquid-liquid calculations.

Movie S1. Cross section of liquid droplet density as it evolves along the nucleation pathway for the example presented in the main text showing the log of the density.

Movie S2. Cross section of liquid droplet density as it evolves along the nucleation pathway for the example presented in the main text showing the density on a linear scale.

Movie S3. Cross section of solid cluster density as it evolves along the nucleation pathway for the example presented in the main text showing the log of the density.

Movie S4. Cross section of solid cluster density as it evolves along the nucleation pathway for the example presented in the main text showing the density on a linear scale.

References (*62*–*65*)