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An Alternative Strategy to Polymorph Recognition at Work: The Emblematic Case of Coronene

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posted on 24.07.2018, 00:00 by Tommaso Salzillo, Andrea Giunchi, Matteo Masino, Natalia Bedoya-Martı́nez, Raffaele G. Della Valle, Aldo Brillante, Alberto Girlando, Elisabetta Venuti
We show that the development of highly accurate density functional theory calculations coupled to low-frequency Raman spectroscopy constitutes a valid method for polymorph characterization alternative/complementary to X-ray. The method is applied here to the temperature-induced, first-order phase transition of coronene, known for a long time, but has remained structurally uncharacterized due to crystal breaking during the process. The astonishing fidelity of the Raman calculated spectra to the experiments allows us to unambiguously identify the low-temperature phase with the β-coronene polymorph, recently reported as new and obtained in the presence of a magnetic field. We also suggest that additional measurements are needed to confirm that a magnetic field can actually drive the growth of a β-polymorph surviving indefinitely at ambient temperature.