高能材料可將大量化學能儲存在分子內，透過斷鍵的方式在短時間內釋放出大量能量，在軍事或民生上都受到廣泛的應用，像是子彈以及火箭的推進器、炸藥、煙火⋯⋯等。探討高能材料時，通常會探討以下性質：反應熱、材料密度、爆炸速度、爆炸壓力、氧平衡以及各種外力刺激的敏感度。一般而言，爆炸性能越高伴隨著越高的敏感度，越高的敏感度代表在儲存和運輸上越不安全，因此科學家們致力於設計出一種能夠兼具高性能及高穩定度的高能材料。而目前有一種材料能夠達到上述需求，就是具有共軛環狀結構的含氮化合物(DNPP，見圖五)，這種化合物的結構為共軛平面，分子間會產生π-π 堆疊使得穩定度提升。且由於具有環張力，造成其生成熱較高，爆炸時也會釋放較多能量，也就代表爆炸性能的提升。除此之外，透過修飾官能基也能影響其爆炸性質。
為了得知炸藥為何具有如此強烈的反應性，本研究以量子化學模擬，尋找高能材料的分解過程。針對單分子反應及雙分子反應分別找到不同的反應路徑，由結果可得知，產生的自由基能有效降低高能材料分解過程所需的能量，使得反應更迅速進行。另外以VASP軟體去計算晶體結構造成的影響，結果顯示晶體結構會抑制NO2自由基的分解，使其穩定性提升。
關鍵字：高能材料 / 炸藥 / 含氮稠環化合物 / 量子力學 / 分子動力學

High energy density materials are a kind of materials that can store a large amount of chemical energies in molecules and release them in a short period of time by breaking bonds. They are widely used in military and people’s livelihood. In terms of properties, the higher the explosives performance, the higher the sensitivity. Higher sensitivity means less safety in storage and transportation. Therefore, scientists dedicate to design high energy density materials that can have both high performance and high stability.
At present, nitrogen-containing compound with a conjugated ring structure is a promising material that can fulfill the requirements. The structure of this compound contains conjugated plane, and π-π stacking between the molecules, which improve the stability. Because of the ring tension, the heat of formation is higher, and more energy will be released when exploding. In addition, the explosive properties can also be affected by modifying functional groups.
In this study, in order to understand why explosives have such strong reactivity, we used quantum mechanical simulation to find out the dissociation pathway. Different dissociation pathways were found for unimolecular reactions and bimolecular reactions. The results indicated that radicals could effectively reduce the reaction energy kinetically, so that the reaction could proceeds more quickly. Furthermore, VASP was used to calculate the influence of the crystal structure, and the results showed that the crystal structure would inhibit the dissociation of NO2 radicals and improved its stability. The results of this study may provide basic information for the further study of this kind of compounds and molecular design of novel HEDMs.
Key words: HEDMs, Explosives, Nitrogen-Containing Fused-Ring Compound, Quantum Mechanical Simulation, MD Simulation

1. Shattuck, M. S., Determination of detonation velocity of explosive compounds using optical techniques. New Mexico Institute of Mining and Technology: 2015.
2. Kamlet, M. J.; Jacobs, S., Chemistry of detonations. I. A simple method for calculating detonation properties of C–H–N–O explosives. The Journal of Chemical Physics 1968, 48 (1), 23-35.
3. Kamlet, M. J.; Ablard, J., Chemistry of detonations. II. Buffered equilibria. The Journal of Chemical Physics 1968, 48 (1), 36-42.
4. Kamlet, M. J.; Dickinson, C., Chemistry of detonations. III. Evaluation of the simplified calculational method for chapman‐jouguet detonation pressures on the basis of available experimental information. The Journal of Chemical Physics 1968, 48 (1), 43-50.
5. Kamlet, M. J.; Hurwitz, H., Chemistry of detonations. IV. Evaluation of a simple predictional method for detonation velocities of C–H–N–O explosives. The Journal of Chemical Physics 1968, 48 (8), 3685-3692.
6. Rothstein, L.; Petersen, R., Predicting High Explosives Detonation Velocity of from their Composition and Structure. ADA 062265, Naval Weapon Station, Verginia: 1978.
7. Stine, J., On predicting properties of explosives–detonation velocity. Journal of energetic materials 1990, 8 (1-2), 41-73.
8. Keshavarz, M. H.; Pouretedal, H. R., An empirical method for predicting detonation pressure of CHNOFCl explosives. Thermochimica Acta 2004, 414 (2), 203-208.
9. Gao, H.; Zhang, Q.; Jean'ne, M. S., Fused heterocycle-based energetic materials (2012–2019). Journal of Materials Chemistry A 2020, 8 (8), 4193-4216.
10. Tang, Y.; He, C.; Imler, G. H.; Parrish, D. A.; Shreeve, J. n. M., Aminonitro groups surrounding a fused pyrazolotriazine ring: a superior thermally stable and insensitive energetic material. ACS Applied Energy Materials 2019, 2 (3), 2263-2267.
11. Xia, H.; Zhang, W.; Jin, Y.; Song, S.; Wang, K.; Zhang, Q., Synthesis of thermally stable and insensitive energetic materials by incorporating the tetrazole functionality into a fused-ring 3, 6-dinitropyrazolo-[4, 3-c] pyrazole framework. ACS applied materials & interfaces 2019, 11 (49), 45914-45921.
12. Yin, P.; He, C.; Jean'ne, M. S., Fused heterocycle-based energetic salts: alliance of pyrazole and 1, 2, 3-triazole. Journal of Materials Chemistry A 2016, 4 (4), 1514-1519.
13. Zhang, C.; Wang, X.; Huang, H., π-stacked interactions in explosive crystals: buffers against external mechanical stimuli. Journal of the American Chemical Society 2008, 130 (26), 8359-8365.
14. Zhang, J.; Zhang, Q.; Vo, T. T.; Parrish, D. A.; Shreeve, J. n. M., Energetic salts with π-stacking and hydrogen-bonding interactions lead the way to future energetic materials. Journal of the American Chemical Society 2015, 137 (4), 1697-1704.
15. Wang, F.; Wang, G.; Du, H.; Zhang, J.; Gong, X., Theoretical studies on the heats of formation, detonation properties, and pyrolysis mechanisms of energetic cyclic nitramines. The Journal of Physical Chemistry A 2011, 115 (47), 13858-13864.
16. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Petersson, G. A.; Nakatsuji, H.; Li, X.; Caricato, M.; Marenich, A. V.; Bloino, J.; Janesko, B. G.; Gomperts, R.; Mennucci, B.; Hratchian, H. P.; Ortiz, J. V.; Izmaylov, A. F.; Sonnenberg, J. L.; Williams; Ding, F.; Lipparini, F.; Egidi, F.; Goings, J.; Peng, B.; Petrone, A.; Henderson, T.; Ranasinghe, D.; Zakrzewski, V. G.; Gao, J.; Rega, N.; Zheng, G.; Liang, W.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Throssell, K.; Montgomery Jr., J. A.; Peralta, J. E.; Ogliaro, F.; Bearpark, M. J.; Heyd, J. J.; Brothers, E. N.; Kudin, K. N.; Staroverov, V. N.; Keith, T. A.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A. P.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Millam, J. M.; Klene, M.; Adamo, C.; Cammi, R.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Farkas, O.; Foresman, J. B.; Fox, D. J. Gaussian 16 Rev. C.01, Wallingford, CT, 2016.
17. Y. Shao, Z. G., E. Epifanovsky, A. T. B. Gilbert, M. Wormit, J. Kussmann, A. W. Lange, A. Behn, J. Deng, X. Feng, D. Ghosh, M. Goldey P. R. Horn, L. D. Jacobson, I. Kaliman, R. Z. Khaliullin, T. Kús, A. Landau, J. Liu, E. I. Proynov, Y. M. Rhee, R. M. Richard, M. A. Rohrdanz, R. P. Steele, E. J. Sundstrom, H. L. Woodcock III, P. M. Zimmerman, D. Zuev, B. Albrecht, E. Alguire, B. Austin, G. J. O. Beran, Y. A. Bernard, E. Berquist, K. Brandhorst, K. B. Bravaya, S. T. Brown, D. Casanova, C.-M. Chang, Y. Chen, S. H. Chien, K. D. Closser, D. L. Crittenden, M. Diedenhofen, R. A. DiStasio Jr., H. Dop, A. D. Dutoi, R. G. Edgar, S. Fatehi, L. Fusti-Molnar, A. Ghysels, A. Golubeva-Zadorozhnaya, J. Gomes, M. W. D. Hanson-Heine, P. H. P. Harbach, A. W. Hauser, E. G. Hohenstein, Z. C. Holden, T.-C. Jagau, H. Ji, B. Kaduk, K. Khistyaev, J. Kim, J. Kim, R. A. King, P. Klunzinger, D. Kosenkov, T. Kowalczyk, C. M. Krauter, K. U. Lao, A. Laurent, K. V. Lawler, S. V. Levchenko, C. Y. Lin, F. Liu, E. Livshits, R. C. Lochan, A. Luenser, P. Manohar, S. F. Manzer, S.-P. Mao, N. Mardirossian, A. V. Marenich, S. A. Maurer, N. J. Mayhall, C. M. Oana, R. Olivares-Amaya, D. P. O’Neill, J. A. Parkhill, T. M. Perrine, R. Peverati, P. A. Pieniazek, A. Prociuk, D. R. Rehn, E. Rosta, N. J. Russ, N. Sergueev, S. M. Sharada, S. Sharmaa, D. W. Small, A. Sodt, T. Stein, D. Stück, Y.-C. Su, A. J. W. Thom, T. Tsuchimochi, L. Vogt, O. Vydrov, T. Wang, M. A. Watson, J. Wenzel, A. White, C. F. Williams, V. Vanovschi, S. Yeganeh, S. R. Yost, Z.-Q. You, I. Y. Zhang, X. Zhang, Y. Zhou, B. R. Brooks, G. K. L. Chan, D. M. Chipman, C. J. Cramer, W. A. Goddard III, M. S. Gordon, W. J. Hehre, A. Klamt, H. F. Schaefer III, M. W. Schmidt, C. D. Sherrill, D. G. Truhlar, A. Warshel, X. Xua, A. Aspuru-Guzik, R. Baer, A. T. Bell, N. A. Besley, J.-D. Chai, A. Dreuw, B. D. Dunietz, T. R. Furlani, S. R. Gwaltney, C.-P. Hsu, Y. Jung, J. Kong, D. S. Lambrecht, W. Liang, C. Ochsenfeld, V. A. Rassolov, L. V. Slipchenko, J. E. Subotnik, T. Van Voorhis, J. M. Herbert, A. I. Krylov, P. M. W. Gill, and M. Head-Gordon., Advances in molecular quantum chemistry contained in the Q-Chem 4 program package. Molecular Physics 2015, 113 (2), 184-215.
18. Choi, C.; Yoo, H.-W.; Goh, E. M.; Cho, S. G.; Jung, Y., Ti (N5)4 as a potential nitrogen-rich stable high-energy density material. The Journal of Physical Chemistry A 2016, 120 (24), 4249-4255.
19. Kresse, G.; Furthmüller, J., Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Physical review B 1996, 54 (16), 11169.
20. Kresse, G.; Furthmüller, J., Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Computational materials science 1996, 6 (1), 15-50.
21. Kresse, G.; Hafner, J., Ab initio molecular-dynamics simulation of the liquid-metal–amorphous-semiconductor transition in germanium. Physical Review B 1994, 49 (20), 14251.
22. Luo, J.; Zhao, X.; Wu, J.; Jang, H. D.; Kung, H. H.; Huang, J., Crumpled graphene-encapsulated Si nanoparticles for lithium ion battery anodes. The journal of physical chemistry letters 2012, 3 (13), 1824-1829.
23. Blöchl, P. E., Projector augmented-wave method. Physical review B 1994, 50 (24), 17953.
24. Kresse, G.; Joubert, D., From ultrasoft pseudopotentials to the projector augmented-wave method. Physical review b 1999, 59 (3), 1758.
25. Perdew, J. P.; Burke, K.; Ernzerhof, M., Generalized gradient approximation made simple. Physical review letters 1996, 77 (18), 3865.
26. Chakraborty, D.; Muller, R. P.; Dasgupta, S.; Goddard, W. A., Mechanism for unimolecular decomposition of HMX (1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine), an ab initio study. The Journal of Physical Chemistry A 2001, 105 (8), 1302-1314.
27. Sharia, O.; Kuklja, M. M., Ab Initio kinetics of gas phase decomposition reactions. The Journal of Physical Chemistry A 2010, 114 (48), 12656-12661.
28. Reichel, M.; Dosch, D.; Klapötke, T.; Karaghiosoff, K., Correlation between structure and energetic properties of three nitroaromatic compounds: bis (2, 4-dinitrophenyl) ether, bis (2, 4, 6-trinitrophenyl) ether, and bis (2, 4, 6-trinitrophenyl) thioether. Journal of the American Chemical Society 2019, 141 (50), 19911-19916.
29. Li, C.; Li, H.; Zong, H.-H.; Huang, Y.; Gozin, M.; Sun, C. Q.; Zhang, L., Strategies for Achieving Balance between Detonation Performance and Crystal Stability of High-Energy-Density Materials. Iscience 2020, 23 (3), 100944.