外电场影响HMX/MDNI复合物感度的理论研究

Theoretical Investigation into the Effects of External Electric Fields upon the Sensitivity of HMX/MDNI Complex

为研究外电场对炸药感度的影响,采用量子力学方法在M06-2X∥B3LYP/6-311++G(d,p)水平上对奥克托今(HMX)/1-甲基-4,5-二硝基咪唑(MDNI)分别施加不同大小的外电场(-0.010~0.010 a.u.),得到不同外电场下的稳定构型。分析了各稳定构型的分子间相互作用、引发键解离能、硝基基团电荷、电子密度拓扑、电子密度转移及表面静电势的变化。结果表明:随着正向外电场的增强,HMX的引发键键长变短,解离能增加,感度降低,负向外电场时则相反;采用B3LYP方法所得3种复合物的解离能与外电场的相关系数分别达到了0.995、0.977和0.982;负向外电场作用下硝基基团所带负电荷减少,使炸药感度增加;电子密度拓扑分析表明,外电场作用下,HMX与MDNI分子间仍存在微弱的氢键作用;电子密度转移分析表明正向外电场增强了引发键的强度;分子表面静电势则进一步表明在正向外电场作用下炸药感度降低,负向时感度增加。

To investigate the effects of external electric field on sensitivity of HMX/MDNI, different external electric fields(-0.010-0.010 a.u.) were employed on M06-2 X//B3LYP/6-311++G(d,p) level by quantum mechanics method. The intermolecular interaction, trigger bond energy, electron density topological, electron density shifts and electrostatic surface potential of complexes were considered with different external electric fields. It shows that trigger bond length is shorter and bond dissociation energy is larger with the increasing of external electric field along the positive direction, while the trend is opposite along the negative direction. The correlation coefficients for 3 complexes(by B3LYP) are 0.995,0.977 and 0.982,respectively.Q_(NO_2) are decreasing with the negative external electric fields, indicating the sensitivity is increasing. Electron density topological analysis shows that there are weak hydrogen bond interactions between HMX and MDNI with external electric fields. Electron density shifts analysis shows that positive external electric field strengthens the trigger bond.Electrostatic surface potential indicates that sensitivity of explosive is decreasing in the positive external electric field, while increasing in the negative direction.