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Ji J, Zhu W. Effects of oxidizing molecules on the thermal decomposition of TTDO by ab initio molecular dynamics simulations. J Mol Graph Model 2022; 116:108270. [PMID: 35843154 DOI: 10.1016/j.jmgm.2022.108270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 06/11/2022] [Accepted: 07/05/2022] [Indexed: 12/15/2022]
Abstract
Oxidizing molecules play a very important role in improving the comprehensive properties of energetic materials. Recently, a series of energetic cocrystals containing 2,4,6-triamino-1,3,5-triazine-1,3-dioxide (TTDO) and oxidizing molecule have been successfully prepared. Therefore, ab initio molecular dynamics were used to simulate the thermal decomposition process of TTDO, TTDO:H2O2, TTDO:HNO3, and TTDO:HClO4 crystals at 3000 K to study the role of oxidizing molecules during the thermal decomposition of TTDO. The initial decomposition paths of the TTDO crystal include N-H bond breaking, C-N bond breaking, and intramolecular and intermolecular H transfers. The formation mechanisms of H2O, N2, and CO2 in the four crystals are completely different. The key formation mechanism of H2O is the combination of O with OH, that of N2 is the formation of the -N-N- structure, and that of CO2 is to form the intermediate CO-R with carbonyl structure that form the fragment with the -O-C-O- structure. All the oxidizers H2O2, HNO3, and HClO4 involve in the formation of H2O, N2, and CO2. The formation mechanisms of urea during the decomposition process of the four crystals are completely different, but the key step is to produce the structure of -N-CO-N-. An analysis of Nx shows that H2O2, HNO3 and HClO4 affect not only the types of Nx, but also its formation mechanisms. Among them, HNO3 has the greatest influence on Nx.
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Affiliation(s)
- Jincheng Ji
- Institute for Computation in Molecular and Materials Science, School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Weihua Zhu
- Institute for Computation in Molecular and Materials Science, School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
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Thermal decomposition mechanisms of energetic CL-20-based co-crystals: quantum molecular dynamics simulations. J Mol Model 2022; 28:326. [PMID: 36138262 DOI: 10.1007/s00894-022-05327-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 09/13/2022] [Indexed: 10/14/2022]
Abstract
The decomposition mechanisms of energetic CL-20:2,4-dinitro-2,4-diazapentane (DNP) and CL-20:2,4-dinitro-2,4-diazaheptane (DNG) co-crystals at high temperatures (1000, 2000, and 3000 K) were studied by density functional tight-binding molecular dynamics (DFTB-MD) simulations. At different temperatures, their decomposition mechanisms are very different. At 1000 K, conformational changes are observed only for the CL-20:DNG co-crystal, in which the CL-20 changes from β-CL-20 to γ-CL-20. When the temperature is increased to 2000 K, CL-20, DNP, and DNG begin to decompose, and there are five paths for the main initial mechanisms. Further increasing the temperature to 3000 K promotes a more complete decomposition. The initial reactions of CL-20 in the two co-crystals have two channels. There are two initial decomposition channels in the DNP molecule and only one channel in the DNG molecule. As the temperature increases, the decomposition products of the two co-crystals are different. Our work may provide the in-depth understanding of the decomposition mechanisms of high-energy CL-20-based co-crystals at high temperatures.
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Bai H, Luo Y, Jiang J, Gou R, Zhang S, Hu W. Molecular dynamics simulation of initial thermal decomposition mechanism of DNTF. J Mol Model 2022; 28:111. [DOI: 10.1007/s00894-022-05095-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 03/15/2022] [Indexed: 10/18/2022]
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Computational Design of High Energy RDX-Based Derivatives: Property Prediction, Intermolecular Interactions, and Decomposition Mechanisms. Molecules 2021; 26:molecules26237199. [PMID: 34885779 PMCID: PMC8659176 DOI: 10.3390/molecules26237199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 11/23/2021] [Accepted: 11/25/2021] [Indexed: 11/17/2022] Open
Abstract
A series of new high-energy insensitive compounds were designed based on 1,3,5-trinitro-1,3,5-triazinane (RDX) skeleton through incorporating -N(NO2)-CH2-N(NO2)-, -N(NH2)-, -N(NO2)-, and -O- linkages. Then, their electronic structures, heats of formation, detonation properties, and impact sensitivities were analyzed and predicted using DFT. The types of intermolecular interactions between their bimolecular assemble were analyzed. The thermal decomposition of one compound with excellent performance was studied through ab initio molecular dynamics simulations. All the designed compounds exhibit excellent detonation properties superior to 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), and lower impact sensitivity than CL-20. Thus, they may be viewed as promising candidates for high energy density compounds. Overall, our design strategy that the construction of bicyclic or cage compounds based on the RDX framework through incorporating the intermolecular linkages is very beneficial for developing novel energetic compounds with excellent detonation performance and low sensitivity.
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Oliveira MAS, Oliveira RSS, Borges I. Quantifying bond strengths via a Coulombic force model: application to the impact sensitivity of nitrobenzene, nitrogen-rich nitroazole, and non-aromatic nitramine molecules. J Mol Model 2021; 27:69. [PMID: 33543327 DOI: 10.1007/s00894-021-04669-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 01/12/2021] [Indexed: 11/28/2022]
Abstract
The quantification of bond strengths is a useful and general concept in chemistry. In this work, a Coulombic force model based on atomic electric charges computed using the accurate distributed multipole analysis (DMA) partition of the molecular charge density was employed to quantify the weakest N-NO2 and C-NO2 bond strengths of 19 nitrobenzene, 11 nitroazole, and 10 nitramine molecules. These bonds are known as trigger linkages because they are usually related to the initiation of an explosive. The three families of explosives combine different types of molecular properties and structures ranging from essentially aromatic molecules (nitrobenzenes) to others with moderate aromaticity (nitroazoles) and non-aromatic molecules with cyclic and acyclic skeletons (nitramines). We used the results to investigate the impact sensitivity of the corresponding explosives employing the trigger linkage concept. For this purpose, the computed Coulombic bond strength of the trigger linkages was used to build four sensitivity models that lead to an overall good agreement between the predicted values and available experimental sensitivity values even when the model included the three chemical families simultaneously. We discussed the role of the trigger linkages for determining the sensitivity of the explosives and rationalized eventual discrepancies in the models by examining alternative decomposition mechanisms and features of the molecular structures.
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Affiliation(s)
- Marco Aurélio Souza Oliveira
- Departamento de Química, Instituto Militar de Engenharia, Praça General Tibúrcio, 80, Rio de Janeiro, RJ, 22290-270, Brazil
| | | | - Itamar Borges
- Departamento de Química, Instituto Militar de Engenharia, Praça General Tibúrcio, 80, Rio de Janeiro, RJ, 22290-270, Brazil.
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Xiang D, Zhu W. Mechanisms and kinetics of initial pyrolysis and combustion reactions of 1,1-diamino-2,2-dinitroethylene from density functional tight-binding molecular dynamics simulations. CAN J CHEM 2019. [DOI: 10.1139/cjc-2019-0141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The density functional tight-binding molecular dynamics approach was used to study the mechanisms and kinetics of initial pyrolysis and combustion reactions of isolated and multi-molecular FOX-7. Based on the thermal cleavage of bridge bonds, the pyrolysis process of FOX-7 can be divided into three stages. However, the combustion process can be divided into five decomposition stages, which is much more complex than the pyrolysis reactions. The vibrations in the mean temperature contain nodes signifying the formation of new products and thereby the transitions between the various stages in the pyrolysis and combustion processes. Activation energy and pre-exponential factor for the pyrolysis and combustion reactions of FOX-7 were obtained from the kinetic analysis. It is found that the activation energy of its pyrolysis and combustion reactions are very low, making both take place fast. Our simulations provide the first atomic-level look at the full dynamics of the complicated pyrolysis and combustion process of FOX-7.
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Affiliation(s)
- Dong Xiang
- College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou, Hubei 434020, China
- Institute for Computation in Molecular and Materials Science, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Weihua Zhu
- Institute for Computation in Molecular and Materials Science, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
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Xie H, Zhu W. Thermal decomposition mechanisms of the energetic benzotrifuroxan:1,3,3‐trinitroazetidine cocrystal using ab initio molecular dynamics simulations. J CHIN CHEM SOC-TAIP 2019. [DOI: 10.1002/jccs.201900169] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Huimin Xie
- Institute for Computation in Molecular and Materials Science, School of Chemical EngineeringNanjing University of Science and Technology Nanjing China
| | - Weihua Zhu
- Institute for Computation in Molecular and Materials Science, School of Chemical EngineeringNanjing University of Science and Technology Nanjing China
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Vargeese AA. Decomposition Kinetics of Substituted Energetic Isowurtzitane Cage Molecules Hexanitrohexaazaisowurtzitane (CL‐20) and TEX: A Comparative Study. ChemistrySelect 2019. [DOI: 10.1002/slct.201900762] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Anuj A Vargeese
- Advanced Centre of Research in High Energy Materials (ACRHEM)University of Hyderabad Hyderabad 500046; India
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Dinitromethyl, fluorodinitromethyl derivatives of RDX and HMX as high energy density materials: a computational study. Struct Chem 2019. [DOI: 10.1007/s11224-019-01366-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Kiselev VG, Goldsmith CF. Accurate Prediction of Bond Dissociation Energies and Barrier Heights for High-Energy Caged Nitro and Nitroamino Compounds Using a Coupled Cluster Theory. J Phys Chem A 2019; 123:4883-4890. [DOI: 10.1021/acs.jpca.9b01506] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vitaly G. Kiselev
- School of Engineering, Brown University, 184 Hope Str., Providence, Rhode Island 02912, United States
- Novosibirsk State University, 2 Pirogova Str., 630090 Novosibirsk, Russia
- Institute of Chemical Kinetics and Combustion SB RAS, 3 Institutskaya Str., 630090 Novosibirsk, Russia
| | - C. Franklin Goldsmith
- School of Engineering, Brown University, 184 Hope Str., Providence, Rhode Island 02912, United States
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Xiang D, Zhu W. Adiabatic and constant volume decomposition process of condensed phase δ-1,3,5,7-tetranitro-1,3,5,7-tetrazocane at high temperatures: Quantum molecular dynamics simulations. J Mol Graph Model 2018; 85:68-74. [PMID: 30099224 DOI: 10.1016/j.jmgm.2018.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/29/2018] [Accepted: 08/03/2018] [Indexed: 11/17/2022]
Abstract
We performed quantum molecular dynamics simulations to investigate the initiation chemistry of condensed phase δ-HMX at high temperatures by maintaining constant energy and volume to model adiabatic initiation process. The decomposition of HMX began by the C-N bond breaking in one molecule and by the C-H bond cleavage in other HMX molecule at 2400 K. At 2700 K, HMX is triggered by only one path that the C-N bond broke and the ring opened. At 3000 K, the decomposition of HMX is triggered by the C-H bond and N-O bond fission in the branch chains. There are seven decomposition channels observed during the whole decomposition stage. The N-O bond cleavage is a dominant reaction pathway. The boat configuration of the HMX molecule caused a new reaction channel to be happened by forming a new N-N bond. Another new reaction channel took place to form a new N-C bond due to intermolecular effects.
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Affiliation(s)
- Dong Xiang
- Institute for Computation in Molecular and Materials Science, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, China
| | - Weihua Zhu
- Institute for Computation in Molecular and Materials Science, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, China.
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