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力学学报  2015 

高速冲击压缩梯恩梯的分子动力学模拟

DOI: 10.6052/0459-1879-14-141, PP. 174-179

Keywords: 冲击压缩,梯恩梯,反应力场,分子动力学

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Abstract:

采用反应力场分子动力学方法模拟了梯恩梯(2,4,6-trinitrotoluene,TNT)冲击压缩过程.冲击压缩完全时,体积压缩至原体积40%,梯恩梯分子分解完毕,体系压力达到峰值.随后稀疏波反向拉伸致大量原子或分子基团飞溅至下游,同时压力开始卸载.密度及粒子速度剖面显示压缩波后方密度较大,粒子基本处于静止状态,且压缩波内存在较大的粒子速度梯度.早期化学反应特征是梯恩梯分子在冲击压缩作用下脱落H,O原子后残基快速聚合形成较大的分子团簇,此阶段和平动—振动弛豫过程相关,并且分子由平动—振动模态转换的时间尺度为0.5ps.产物识别分析显示梯恩梯在高速冲击压缩下致C—H,O=N键断裂,脱落的原子部分形成OH,H2,H2O,N2,部分H,O原子游离在体系中.含碳团簇分析显示,冲击压缩作用致体系中含碳团簇的摩尔质量逐渐累积.体系内含碳团簇中O/C,H/C,N/C原子数量比值逐渐趋于平衡(O/C=0.680,H/C=0.410,N/C=0.284),且均小于初始结构中的比值.

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