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  • Fundamentally intertwined: anharmonic intermolecular interactions dictate both thermal expansion and terahertz lattice dynamics in molecular crystals
Title: Fundamentally intertwined: anharmonic intermolecular interactions dictate both thermal expansion and terahertz lattice dynamics in molecular crystals
We investigate the anisotropic thermal expansion behavior of a co- crystalline system composed of 4,40-azopyridine and trimesic acid (TMA-azo). Using variable-temperature single-crystal X-ray diffrac- tion (SC-XRD), low-frequency Raman spectroscopy, and terahertz time-domain spectroscopy (THz-TDS), we observe significant temperature-induced shifting and broadening of the vibrational absorption features, indicating changes in the intermolecular potential. Our findings reveal that thermal expansion is driven by anharmonic interactions and the potential energy topography, rather than increased molecular dynamics. Density functional the- ory (DFT) simulations support these results, highlighting significant softening of the potential energy surface (PES) with temperature. This comprehensive approach offers valuable insights into the relationship between structural dynamics and thermal properties, providing a robust framework for designing materials with tailored thermal expansion characteristics.  more » « less
Award ID(s):
2055402 2046483
PAR ID:
10568351
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Publisher / Repository:
RSC
Date Published:
Journal Name:
Chemical Communications
Volume:
60
Issue:
84
ISSN:
1359-7345
Page Range / eLocation ID:
12169 to 12172
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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