运用从头算分子动力学模拟高温耦合爆轰压力条件下α-RDX的分解机理

摘要

The initiation and subsequent decomposition mechanisms ofα-RDX crystal under high temperature (3000 K) coupled with detonation pres-sure (34.5 GPa) were studied by ab initio molecular dynamics simulations.The crystal structure of RDX was relaxed using two types of van der Waals corrections such as PBE-G06 and PBE-TS functional at ambient conditions.The results indicate that the PBE-G06 functional is much suitable for studying α-RDX.Results show that the decomposition of α-RDX is triggered by the homolysis of the C—H bond.The DOS clearly validates that the C—H bond is broken.The elimination reaction of HONO during the decomposition is observed.The primary reactions for producing NO2, NO, N2O, N2, HONO, N2O4, H, O—H, H2O, and CO2 occur at very early stages.After the initiation of RDX, there are three different subsequent de-composition pathways.There are three main interesting subsequent decomposition paths include: (1 ) the C—N bond hemolysis triggers the other C—N bonds of this ring to break; (2) the dissociation of N—NO2 bond releases NO2 gas; (3) the H radical attacks the O atom to release O—H radical by forming O—H bond.%运用从头算分子动力学模拟了α-黑索今(RDX)晶体在高温(3000K)耦合爆轰压力(34.5GPa)下的初始和随后的分解机理.采用两种范德瓦尔斯修的修正方法(PBE-G06和PBE-TS)环境条件下对RDX的晶体结构进行了优化.结果表明,PBE-TS非常合适优化RDX.RDX分解中,C—H键均裂引发α-RDX分解.态密度的结果也证明了C—H键断键的现象.分解过程中发生了HONO的消去反应.产生NO2、NO、N2O、N2、HONO、N2O4、H、O—H、H2O和CO2为主要反应,发生在早期阶段.同时,RDX引发后的三种不同的分解途径分别为(1)C—N断键引发该环中其它C—N键断裂;(2)N—NO2断键并且释放NO2气体;(3)H自由基和氧原子碰撞形成O—H键后释放O—H自由基.