Probing into the theory of impact sensitivity: propelling the understanding of phonon-vibron coupling coefficients

• Published in: Physical chemistry chemical physics : PCCP Vol. 26; no. 9; pp. 7695 - 775
• Main Authors: Liu, Wei-Hong, Zeng, Wei, Liu, Fu-Sheng, Liu, Zheng-Tang, Liu, Qi-Jun
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 28.02.2024
• Subjects: Coupling coefficients; Damping; Energetic materials; Impact loads; Impact response; Phonons; Regression analysis; Vibrational spectra
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/d3cp06083g

The determination of impact sensitivity of energetic materials traditionally relies on expensive and safety-challenged experimental means. This has instigated a shift towards scientific computations to gain insights into and predict the impact response of energetic materials. In this study, we refine the phonon-vibron coupling coefficients ζ in energetic materials subjected to impact loading, building upon the foundation of the phonon up-pumping model. Considering the full range of interactions between high-order phonon overtones and molecular vibrational frequencies, this is a pivotal element for accurately determining phonon-vibron coupling coefficients ζ . This new coupling coefficient ζ relies exclusively on phonon and molecular vibrational frequencies within the range of 0-700 cm −1 . Following a regression analysis involving ζ and impact sensitivity ( H 50 ) of 45 molecular nitroexplosives, we reassessed the numerical values of damping factors, establishing a = 2.5 and b = 35. This coefficient is found to be a secondary factor in determining sensitivity, secondary to the rate of decomposition propagation and thermodynamic factor (heat of explosion). Furthermore, the relationship between phonon-vibron coupling coefficients ζ and impact sensitivity was studied in 16 energetic crystalline materials and eight nitrogen-rich energetic salts. It was observed that as the phonon-vibron coupling coefficient increases, the tendency for reduced impact sensitivity H 50 still exists. The impact of the damping factor a and b on phonon-vibron coupling strength.