CL-20/TNT共晶炸药的分子动力学研究

doi:10.7503/cjcu20150605

摘要/Abstract

摘要：

运用分子动力学(MD)方法, 选择凝聚态分子势能优化力场(COMPASS), 对六硝基六氮杂异伍兹烷(ε-CL-20)、 2,4,6-三硝基甲苯(TNT)晶体及其等摩尔比的CL-20/TNT混合炸药和共晶炸药进行不同温度下恒定粒子数等压等温(NPT)系综模拟研究. 结果表明, CL-20/TNT共晶的内聚能密度(CED)和结合能随温度的升高逐渐减小; 共晶的CED比混合炸药的大, 结合能是混合炸药的2倍多, 预示其稳定性明显增强. 对相关函数和局部放大结构显示共晶中组分分子间作用主要来自TNT中H和CL-20中O以及CL-20中H和TNT中O之间形成的氢键. 通过波动法求得的弹性力学性能结果表明, CL-20/TNT共晶的拉伸模量(E)、体积模量(K)和剪切模量(G)介于ε-CL-20和TNT晶体之间, 且随温度的升高而下降, 符合一般预期; 但共晶炸药的柯西压(C₁₂-C₄₄, C_ij弹性系数)、 K/G和泊松比(ν)均比其组分炸药ε-CL-20和TNT高得多, 预示该共晶具有异常高的延展性和弹性伸长, 主要是二组分呈层状交替排列且之间存在较强相互作用所致.

关键词: CL-20/TNT共晶炸药, 混合炸药, 力学性能, 对相关函数, 分子动力学

Abstract:

Molecular dynamics(MD) simulation was conducted for 2,4,6,8,10,12-hexanitrohexaazaiso-wurtzitane(ε-CL-20) and 2,4,6-trinitrotoluene(TNT) crystal, CL-20/TNT cocrystal with equal molar ratio and CL-20/TNT composite with equal molar ratio using COMPASS force field with isothermal-isobaric(NPT) ensembles at different temperatures. Their structures, interactions between different components and mechanical properties were investigated. The cohesive energy density(CED) of the cocrystal decreases with rising temperature, and is greater than that of the composite. The binding energy(E_bind) between two components of the cocrystal also decreases gradually with rising temperature, and is twice times as strong as that of the CL-20/TNT composite. In addition, pair correlation function analysis and enlarged local structure show that hydrogen bonds exist between the two components in the cocrystal and these bonds are mainly formed between H atoms in TNT and O atoms in CL-20, and H atoms in CL-20 and O atoms in TNT. The values of the tensile, bulk and shear modulus(E, K, G) for CL-20/TNT cocrystal fall in between those for ε-CL-20 and TNT crystals and decrease with increasing temperature, which agrees with general expectation. However, the Cauchy pressure(C₁₂-C₄₄), K/G and Poisson’s ratio(ν) for CL-20/TNT cocrystal are much larger than those for the two crystals, which predicts the cocrystal has much higher ductility and elastic elongation.

Key words: CL-20/TNT cocrystal explosive, Composite explosive, Mechanical property, Pair correlation function, Molecular dynamics

中图分类号:

O641
TJ55

TrendMD:

刘强, 肖继军, 张将, 赵峰, 何正华, 肖鹤鸣. CL-20/TNT共晶炸药的分子动力学研究. 高等学校化学学报, 2016, 37(3): 559.

LIU Qiang, XIAO Jijun, ZHANG Jiang, ZHAO Feng, HE Zhenghua, XIAO Heming. Molecular Dynamics Simulation on CL-20/TNT Cocrystal Explosive^†. Chem. J. Chinese Universities, 2016, 37(3): 559.

图/表 12

参考文献 32

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T/K	a/nm	b/nm	c/nm	α/(°)	β/(°)	γ/(°)	ρ/(g·cm^-3)	V/nm³
95	0.935	1.958	2.470	90.00	90.00	90.00	1.94	4.521
	(0.004)	(0.009)	(0.005)	(0.18)	(0.14)	(0.13)	(0.01)	(0.011)
195	0.872	2.216	2.452	90.02	90.02	89.99	1.86	4.739
	(0.014)	(0.011)	(0.007)	(0.36)	(0.25)	(0.22)	(0.01)	(0.016)
245	0.878	2.210	2.462	90.01	90.01	90.00	1.85	4.775
	(0.003)	(0.005)	(0.009)	(0.42)	(0.27)	(0.25)	(0.01)	(0.179)
295	0.882	2.208	2.473	90.00	90.00	90.00	1.84	4.815
	(0.007)	(0.020)	(0.010)	(0.44)	(0.31)	(0.31)	(0.01)	(0.023)
345	0.886	2.211	2.483	89.99	89.99	90.00	1.82	4.860
	(0.008)	(0.021)	(0.011)	(0.49)	(0.34)	(0.33)	(0.01)	(0.024)
395	0.892	2.212	2.491	90.02	90.01	90.00	1.80	4.912
	(0.009)	(0.024)	(0.012)	(0.53)	(0.37)	(0.36)	(0.01)	(0.027)
Exp.^[5]	0.967	1.937	2.469	90.00	90.00	90.00	1.91	4.626

T/K	a/nm	b/nm	c/nm	α/(°)	β/(°)	γ/(°)	ρ/(g·cm^-3)	V/nm³
95	0.935	1.958	2.470	90.00	90.00	90.00	1.94	4.521
	(0.004)	(0.009)	(0.005)	(0.18)	(0.14)	(0.13)	(0.01)	(0.011)
195	0.872	2.216	2.452	90.02	90.02	89.99	1.86	4.739
	(0.014)	(0.011)	(0.007)	(0.36)	(0.25)	(0.22)	(0.01)	(0.016)
245	0.878	2.210	2.462	90.01	90.01	90.00	1.85	4.775
	(0.003)	(0.005)	(0.009)	(0.42)	(0.27)	(0.25)	(0.01)	(0.179)
295	0.882	2.208	2.473	90.00	90.00	90.00	1.84	4.815
	(0.007)	(0.020)	(0.010)	(0.44)	(0.31)	(0.31)	(0.01)	(0.023)
345	0.886	2.211	2.483	89.99	89.99	90.00	1.82	4.860
	(0.008)	(0.021)	(0.011)	(0.49)	(0.34)	(0.33)	(0.01)	(0.024)
395	0.892	2.212	2.491	90.02	90.01	90.00	1.80	4.912
	(0.009)	(0.024)	(0.012)	(0.53)	(0.37)	(0.36)	(0.01)	(0.027)
Exp.^[5]	0.967	1.937	2.469	90.00	90.00	90.00	1.91	4.626

Sample	T/K	vdW energy/(kJ·cm^-3)	Electrostatic energy/(kJ·cm^-3)	CED/(kJ·cm^-3)
CL-20/TNT cocrystal	195	0.37(0.01)	0.54(0.01)	0.91(0.01)
	245	0.36(0.00)	0.52(0.01)	0.88(0.01)
	295	0.36(0.00)	0.50(0.01)	0.86(0.01)
	345	0.35(0.00)	0.48(0.01)	0.83(0.01)
	395	0.34(0.00)	0.47(0.01)	0.81(0.01)
CL-20/TNT composite	295	0.31(0.01)	0.45(0.01)	0.76(0.01)

Sample	T/K	vdW energy/(kJ·cm^-3)	Electrostatic energy/(kJ·cm^-3)	CED/(kJ·cm^-3)
CL-20/TNT cocrystal	195	0.37(0.01)	0.54(0.01)	0.91(0.01)
	245	0.36(0.00)	0.52(0.01)	0.88(0.01)
	295	0.36(0.00)	0.50(0.01)	0.86(0.01)
	345	0.35(0.00)	0.48(0.01)	0.83(0.01)
	395	0.34(0.00)	0.47(0.01)	0.81(0.01)
CL-20/TNT composite	295	0.31(0.01)	0.45(0.01)	0.76(0.01)

Sample	T/K	E_bind/ (kJ·mol^-1)	Nonbond energy/ (kJ·mol^-1)	vdW energy/ (kJ·mol^-1)	Repulsive energy/ (kJ·mol^-1)	Dispersive energy/ (kJ·mol^-1)	Electrostatic energy/ (kJ·mol^-1)
CL-20/TNT cocrystal	195	178.90(0.37)	178.90(0.37)	65.73(0.21)	-181.76(0.77)	247.48(0.65)	113.17(0.39)
	245	176.77(0.26)	176.77(0.26)	65.94(0.24)	-178.47(0.60)	244.41(0.63)	110.83(0.31)
	295	174.19(0.30)	174.19(0.44)	65.50(0.39)	-176.72(1.32)	242.22(1.02)	108.69(0.64)
	345	169.43(0.42)	169.43(0.42)	64.78(0.26)	-170.80(0.99)	235.58(0.82)	104.65(0.34)
	395	166.18(0.65)	166.18(0.65)	63.82(0.39)	-166.96(1.05)	230.78(0.85)	102.36(0.39)
CL-20/TNT composite	295	75.27(0.42)	75.27(0.42)	29.66(0.19)	-74.03(0.62)	103.69(0.68)	45.61(0.29)