Session: Physical Chemistry Poster:

The enhanced sampling technique well-tempered metadynamics enables frequent transitions among kinetically isolated states. In this work, metadynamics is invoked to explore the energetic landscape along a crystallization reaction coordinate. States are identified using characteristic peaks in the X-Ray Diffraction spectra as a collective variable (CV) via the Debye scattering function. The “goodness” of the prescribed CV is assessed by correlating intermediate structures with CV values along the crystallization pathway. Aluminum oxide (Al₂O₃) is presented as a test system, as it is known to exhibit a series of ordered, metastable structures (polymorphs) during crystallization. The energetic landscape of bulk Al₂O₃ crystallization is explored near the melting point, while identifying transition barriers among polymorphs. Further structural evaluation among polymorphs is performed using the Steinhardt order parameter. Structural correspondence and kinetic barriers identified using a good CV rationalize the progress of sequential phases during Al₂O₃ crystallization.

Jordan Schmidt

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