Correlating Phonons and Deformations: A Method for Structural Phase Transformation Analysis in Metal-Organic Frameworks

Abstract

We present a methodology for phonon-deformation correlation analysis, aiming to quantify and predict the influences of phonon-mode-driven deformations on structural phase transitions. This approach has been rigorously tested on a range of materials, including the ZrO2 crystal, molecular crystal dimethylaminoborane, and three MOFs: ZIF-8, MIL-53, and JUK-8. The analysis allowed for a consistent identification of key phonon modes that drive phase transitions. The strength of our method is its ability to discern between transitions triggered by specific soft modes and those driven by a more collective mechanism. This differentiation provides a deeper understanding of material behaviors, revealing both individual and collective modes of contribution to phase transitions. For materials with intricate structures and phonon spectra, such as JUK-8, our approach offers a collective spectral representation, simplifying the challenge of evaluating individual modes and highlighting frequency regimes associated with potential structural modifications. Notably, our analysis suggests the significance of low-energy phonons in first-order transitions. This methodology offers a comprehensive perspective, especially for materials with complex phonon characteristics where traditional individual mode analysis may be too complicated.