National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China.
J Phys Chem A. 2010 Jan 21;114(2):1082-92. doi: 10.1021/jp9090969.
A first-principles plane-wave method with an ultrasoft pseudopotential scheme in the framework of the generalized gradient approximation (GGA) was used to calculate the lattice parameters, bulk modulus and its pressure derivative, energy band structures, density of states, phonon density of states, thermodynamic properties, and absorption spectra of solid beta-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (beta-HMX). The current study is focused on the thermodynamics and electronic properties that were not reported previously. The bulk modulus and its pressure derivative are also consistent with experimental data and other theoretical results. From the results for the band gaps and density of states, it was found that beta-HMX has the tendency to become a semiconductor with increasing pressure. As the temperature increases, the heat capacity, enthalpy, product of temperature and entropy, and Debye temperature all increase, whereas the free energy decreases. The optical absorption coefficients shift to higher frequencies/energies with increasing pressure. The present study leads to a better understanding of how energetic materials respond to compression.
采用基于广义梯度近似（GGA）的第一性原理平面波方法和超软赝势方案，计算了固体β-八氢-1,3,5,7-四硝基-1,3,5,7-四氮杂环辛烷（β-HMX）的晶格参数、体弹模量及其压力导数、能带结构、态密度、声子态密度、热力学性质和吸收光谱。本研究重点关注以前未报道过的热力学和电子性质。体弹模量及其压力导数也与实验数据和其他理论结果一致。从能带隙和态密度的结果可以发现，β-HMX 随着压力的增加有成为半导体的趋势。随着温度的升高，热容、焓、温度和熵的乘积以及德拜温度都增加，而自由能则降低。光学吸收系数随着压力的增加向更高的频率/能量移动。本研究有助于更好地理解含能材料对压缩的响应。
