外电场中1,4-二硝基咪唑-N-氧化物感度的理论研究

为探明外电场中炸药感度的变化规律,借助B3LYP/6-311++G(2d,p)和M06-2X/6-311++G(2d,p)理论方法,研究了外电场方向和强度的变化对1,4-二硝基咪唑-N-氧化物(1,4-DNIO)炸药潜在引发键的键长、硝基电荷、键离解能及撞击感度、静电火花感度和冲击起爆压力的影响。结果表明,在无电场和外电场作用下,N─NO2是最可能的引发键,其次是N→O,最后是C─NO2键。沿N→O、C─NO2键轴正方向和N─NO2负方向的外电场使N→O和C─NO2键离解能减小、N─NO2键离解能增大、H50增大、撞击感度降低;与上述反方向的外电场对引发键强度和撞击感度的影响正好相反。引发键键长、AIM电子密度、硝基电荷、键离解能和H50的变化量分别与外电场强度之间呈良好的线性关系,大多数情况下,相关系数R2>0.9500。外电场对电火花感度和冲击起爆压力的影响不大,外电场由-0.010 a.u.变化到0.010 a.u.,变化值分别小于0.5 J和0.15 MPa。

Theoretical Prediction of the Sensitivity of 1,4-Dinitroimidazole-N-oxide in the External Electric Fields

In order to explore the variation rule of explosives′ sensitivity in the external electric field,the bond lengths,nitro charges,bond dissociation energies of the potential trigger linkages and the impact sensitivities,electrostatic spark sensitivities as well as shock initiation pressures of the 1,4-dinitroimidazole-N-oxide(1,4-DNIO)explosive were investigated by the B3 LYP/6-311++G(2 d,p)and M06-2 X/6-311++G(2 d,p)levels of theory. Results show that the N─NO2 bond is the most likely trigger linkage in the initiation reaction of explosive,followed by N→O,and finally the C─NO2 bond in the external electric fields and the absence of the electric fields. Under the external electric fields along the positive directions of the N→O and C─NO2 bond axes as well as the negative direction of the N─NO2 bond axis,the dissociation energies of the N→O and C─NO2 bonds are de-creased,while those of N─NO2 bond are increased,leading to the increases of theH50 values and thus the decreases of the im-pact sensitivities. The opposite conclusion is drawn when the explosives are in the external electric fields with the reverse directions against the above cases. The changes in the bond lengths(ΔR),electron density values(Δρ),nitro charges(ΔQ),bond dissociation energy(ΔBDEs)of the trigger linkages and thoes in the impact sensitivities(ΔH50)show good linear relationships with the external electric field strengths,respectively. In most cases,the values of correlation coefficient R2 are larger than0.9500. The external electric fields have little effect on the electrostatic spark sensitivities or shock initiation pressures,accompanied by the variations lower than 0.5 J and 0.15 MPa with the field strengths from–0.0010 a.u. to 0.0010 a.u.,respectively.