Uncovering the Connection Between Low-Frequency Dynamics and Phase Transformation Phenomena in Molecular Solids

The low-frequency motions of molecules in the condensed phase have been shown to be vital to a large number of physical properties and processes. However, in the case of disordered systems, it is often difficult to elucidate the atomic-level details surrounding these phenomena. In this work, we have...

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Bibliographic Details
Published in:Physical review letters 2018-05, Vol.120 (19), p.196002-196002, Article 196002
Main Authors: Ruggiero, Michael T, Zhang, Wei, Bond, Andrew D, Mittleman, Daniel M, Zeitler, J Axel
Format: Article
Language:English
Subjects:
Camphor
Density functional theory
Molecular dynamics
Order-disorder transformations
Phase transitions
Physical properties
X-ray diffraction
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Summary:The low-frequency motions of molecules in the condensed phase have been shown to be vital to a large number of physical properties and processes. However, in the case of disordered systems, it is often difficult to elucidate the atomic-level details surrounding these phenomena. In this work, we have performed an extensive experimental and computational study on the molecular solid camphor, which exhibits a rich and complex structure-dynamics relationship, and undergoes an order-disorder transition near ambient conditions. The combination of x-ray diffraction, variable temperature and pressure terahertz time-domain spectroscopy, ab initio molecular dynamics, and periodic density functional theory calculations enables a complete picture of the phase transition to be obtained, inclusive of mechanistic, structural, and thermodynamic phenomena. Additionally, the low-frequency vibrations of a disordered solid are characterized for the first time with atomic-level precision, uncovering a clear link between such motions and the phase transformation. Overall, this combination of methods allows for significant details to be obtained for disordered solids and the associated transformations, providing a framework that can be directly applied for a wide range of similar systems.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.120.196002