On the importance of low-frequency modes in predicting pressure-induced phase transitions
Anna Hoser1, Aleksandra Zwolenik1, Anna Makal1
1Faculty of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089, Warszawa, Poland. am.makal@uw.edu.pl.
Abstract:
The occurrence of ultra-low frequency oscillation mode as observed by means of periodic DFT calculations at Γ point in a molecular crystal at ambient conditions can be a valuable predictor of imminent pressure-induced phase transition. We illustrate it with a series of polymorphs of diacetyl-pyrenes, for two of which such soft-modes indicated the trajectory of pressure-induced structural reorganization at ≈0.8 GPa. Notably, susceptibility to pressure-induced phase transformations could not be predicted based on material's thermodynamic characteristics, and there were no unequivocal clues in their crystal packing.
Related Concept Videos
Phase Transitions
Sound as Pressure Waves
The pressure fluctuation depends on the difference in displacements between the successive points in the...
Phase Diagram
Phase Changes
A substance melts or freezes at a temperature called its melting point and boils or condenses at its boiling point. These temperatures depend on pressure. High pressure favors the denser form of the substance, so typically, high pressure...
Phase Diagrams
Phase Transitions: Melting and Freezing


