(544a) Enhanced Sampling Molecular Dynamics Simulations of Polymorphism in Molecular Crystals
AIChE Annual Meeting
2023
2023 AIChE Annual Meeting
Computational Molecular Science and Engineering Forum
Recent Advances in Molecular Simulation Methods II
Thursday, November 9, 2023 - 3:30pm to 3:42pm
Herein, we used MD simulations and dimensionality reduction algorithms to describe conformational polymorphic transitions of CL-20, a complex energetic material with three anhydrous conformational polymorphs (β, γ, and ϵ) at ambient pressure.1 We demonstrate that a local molecular CV obtained from short gas phase simulations of isolated conformers can drive polymorphic phase transitions. We successfully converge the FES of the system and obtain the correct qualitative thermodynamic stability order for the three polymorphs. Moreover, we identified several defect and intermediate forms, which are local minima in FES. We next investigate polymorphism in a phosphorescent organic material by combing descriptors of molecular orientation and global molecular packing. The approach allows for identifying polymorphic transitions into new forms. These findings demonstrate the benefits of combining data-driven approaches with biased MD simulations to describe polymorphism in complex systems and find new strategies to obtain desired molecular polymorphs.
[1] Collective Variables for Conformational Polymorphism in Molecular Crystals, Oren Elishav, Roy Podgaetsky, Olga Meikler, and Barak Hirshberg, The Journal of Physical Chemistry Letters 2023 14 (4), 971-976, DOI: 10.1021/acs.jpclett.2c03491