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固相硝基甲烷相变的第一性原理计算
引用本文:张力,陈朗.固相硝基甲烷相变的第一性原理计算[J].物理学报,2014,63(9):98105-098105.
作者姓名:张力  陈朗
作者单位:北京理工大学爆炸科学与技术国家重点实验室, 北京 100081
摘    要:研究极端条件下固相分子晶体含能材料的相变机理,对于人们认识固相含能材料的爆轰反应有着重要的意义.采用基于校正密度泛函理论的第一性原理方法研究固相硝基甲烷在静水压下的行为.分析晶格参数a,b和c轴随压强的变化,发现在1 GPa到12 GPa时晶格参数出现不连续的变化,表明体系发生相变.在相变时最大的二面角从155.3?增加到177.5?,二面角的增加限制CH3官能团自由旋转,使得C-N和C-H键的键长发生变化.在相变之前,体系主要存在由C-H···O组成的分子间的氢键,而在相变之后存在分子内的H···O和分子间C-H···O组成的氢键.此外通过对硝基甲烷体系的电子结构进行计算,发现相变会影响带隙随压强的变化,而且还会影响费米能级附近的态密度结构.

关 键 词:相变  硝基甲烷  校正密度泛函理论
收稿时间:2013-11-19

First principles calculations of solid phase transition of nitromethane
Zhang Li,Chen Lang.First principles calculations of solid phase transition of nitromethane[J].Acta Physica Sinica,2014,63(9):98105-098105.
Authors:Zhang Li  Chen Lang
Abstract:The solid phase transition in crystals prepared from molecular energetic materials under extreme conditions is important for understanding the detonation mechanisms. By applying the first principles density functional calculations, a detailed theoretical study of the lattice parameters and molecular structures, equations of state, densities of state for solid nitromethane is reported. By analyzing the pressure dependence of lattice parameters, a sudden change of the lattice parameters occurs between 10-12 GPa, implying that a transition has taken place. It is also found that the maximum dihedral angle of H-C-N-O has increased from 155.3° to 177.5°, indicating that a rotation of the methyl group from a staggered to an eclipsed conformation occurs in the pressure range 11–12 GPa. Before the phase transition, the intramolecular O … H–C interactions are mainly of hydrogen bonds. After the phase transition, the intramolecular and intermolecular O … H interactions are mainly of the hydrogen bonds. Phase transition also affects the reduced ratio of band gap and the density of state near the Fermi level.
Keywords: phase transition nitromethane DFT-D
Keywords:phase transition  nitromethane  DFT-D
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