外电场对HMX/DMI共晶感度影响的理论研究

Theoretical Insight into the Effects of External Electric Field on Cocrystal HMX/DMI

为研究外电场对共晶含能材料HMX/DMI感度的影响,分别采用DFT-B3LYP-D3、M06-2X-D3和ωB97XD方法,在6-311+G(d,p)水平下,对HMX/DMI的稳定构型施加±0.005a.u.、±0.010a.u.、0.00a.u.的外电场,分析了电子密度转移、硝基基团电荷、分子表面静电势及引发键变化。结果表明,施加正向外电场时,电场强度越大,炸药感度越高。施加负向外电场时,电场强度越大,炸药感度越低;随着负向外加电场的增强,引发键电子云密度越大,引发键强度增大,导致HMX/DMI感度降低;负向外加电场增加,硝基基团所带负电荷由0.126e增至0.325e,感度降低;分子表面静电势研究分析表明,施加负向电场时,分子表面静电势增大,共晶感度降低;引发键变化分析表明,负向外加电场强度增加,引发键键长由0.1386nm降至0.1367nm,引发键键解离能由180.252kJ/mol增加到180.782kJ/mol,共晶化合物感度降低。

To clarify the influence of external electric field on the sensitivity of energetic HMX/DMI cocrystal material,various external electric fields(±0.005,±0.010,0.00a.u.)were applied on the stable configuration and corresponding electron density shift,nitro group charge,molecular surface electrostatic potential and trigger bond change were analyzed computationally through DFT-B3LYP-D3,M06-2X-D3 andωB97XD methods with the 6-311+G(d,p)basis sets.The results show that the sensitivity of HMX/DMI was high/low when the applied external electric field was positive/negative.When the negative external electric field was stronger,the density of the bond electron cloud was higher as well as the bond strength of the trigger bonds.The negative charge of the nitro group increases from 0.126e to 0.325e when the negative external electric field was applied,which results in the lower sensitivity of HMX/DMI.The electrostatic surface potential(ESP)illustrated that the higher ESP is,the lower sensitivity of cocrystals is when using the negative external electric field.Trigger bond change analysis shows that the bond length of the trigger bond reduced from 0.1386nm to 0.1367nm,the dissociation energy of the trigger bond increased from 180.252kJ/mol to 180.782kJ/mol,and the sensitivity of the cocrystal compound decreased,while increasing the negative external electric field strength.