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用密度泛函理论在B3LYP/6-311++G(2d,2P)计算水平上对硝基甲烷分子进行了结构优化、频率和热化学分析.发现:在相同温度条件下改变压强,分子熵函数产生了改变,当温度和压强条件相同时,对于不同物质熵函数的改变是相同的.以热力学理论中麦克斯韦关系为基础,通过计算等温过程中分子的熵函数对压强的变化率,用数值拟合方法得到不同压强条件下分子温度的表达式:T=T0+(1-B)[18.3858+0.5392P]V0,式中T0、V0分别表示分子系统初态的温度和体积,T、V分别表示系统在末态的温度和体积,B是体积的压缩比.在选定参数的情况下该表达式可以计算不同压强条件下CHNO含能材料的分子温度.同时,以硝基甲烷为验证,选取基本参数V0和B,计算其在C-J条件对应的爆压14GPa下,分子温度为3461K,对应爱因斯坦温度,相当于3228cm-1的能量,在实验中该能量足以激发硝基甲烷分子内振动能量重新分配过程,有可能激发C-N键的红外振动而引起单分子分解反应的发生.因此,此表达式可用于预测含能材料撞击点火过程单分子分解可能的反应通道.
Nitro methane molecules were structurally optimized, frequency and thermochemically analyzed by density functional theory at the B3LYP / 6-311 ++ G (2d, 2P) computational level. It was found that changing pressure, molecular entropy at the same temperature Function changes when the temperature and pressure conditions are the same, for different material entropy function changes are the same.Taking thermodynamics Maxwell relationship as the basis, by calculating the isothermal process of molecular entropy function of the rate of change of pressure, using numerical T = T0 + (1-B) [18.3858 + 0.5392P] V0, where T0 and V0 denote the temperature and volume of the initial state of the molecular system, respectively, and T and V denote the temperature and volume of the molecular system Which indicates the system temperature and volume at the final state and B is the volumetric compression ratio.The expression can be used to calculate the molecular temperature of CHNO energetic materials under different pressure conditions with the selected parameters.At the same time, Select the basic parameters V0 and B, calculated under the CJ conditions corresponding to the explosion pressure 14GPa, the molecular temperature of 3461K, corresponding to the Einstein temperature, the equivalent of 3228cm-1 energy in the experiment sufficient energy to stimulate nitromethane molecules Vibrational energy redistribution Process, it is possible to stimulate the infrared vibration of the C-N bond to cause the monomolecular decomposition reaction.Therefore, this expression can be used to predict the possible reaction channel of the monomolecular decomposition of the energetic material during the impact ignition process.