HMX状态方程与弹性性能的分子动力学研究

利用COMPASS力场，采用NPT系综对β-HMX晶体进行了温度为295K，压力为0—27GPa的分子动力学模拟并进行静态力学分析。研究了β-HMX的压缩各向异性，得到了295K下β-HMX的等温线，用不同状态方程对结果进行拟合，求得了零压下β-HMX体积模量民及其关于p的一阶导数K＇0。计算结果表明，用不同方程拟合得到的K0和K＇0存在差异。通过静态力学分析，得到了弹性系数以及各模量随压力的变化情况，通过对G／K与C12-C44（柯西压）的研究发现JB-HMX的硬度随着压力的增大而增大，在大压力作用下材料由脆性到韧性转变。

Molecular Dynamics Simulation of Isotherm and Elastic Properties of HMX

The isotherms and elastic properties of β-HMX crystals were calculated through molecular simulations in NPT ensemble using COMPASS force field. The isotherms of β-HMX simulated were in reasonable agreement with experiments. The pressure-induced changes of the lattice parameters showed the anisotropic compression of β-HMX. The bulk modulus K_0 and its pressure derivative K'_0 were obtained by fitting the isotherms to different equations of state. However,the values of K_0 and K'_0 obtained from the isotherm are sensitive to the fitting forms of equations of state. The elastic constants and modulus were calculated by statistic analysis mode at different pressures in the range of 0 ～27 Gpa. Cauchy pressure C_(12)-C_(44) and G/K ratios were also calculated which indicated that β-HMX would become harder as the pressure increased, and as well the β-HMX elastic property transformed from brittleness to ductibility.