Using dispersion corrected density functional theory, we comprehensively explore the structure and the Raman spectra of hexanitrohexaazaisowurtzitane (CL-20) crystal under hydrostatic and uniaxial compression. Through hydrostatic compression, we verify that PBE-D2 scheme can accurately describe the crystal structure under zero pressure and high pressure. Along different orientation compressions, the CL-20 crystal exhibits considerable anisotropy in principal stresses and shear stresses. The compression effects on the vibration properties of CL-20 are further analyzed. Compression along the [100] orientation induces some anomalous changes for vibrational modes of the nitro groups, which are associated with changes of the spatial orientation of the nitro groups. This work is expected to shed light on the anisotropic behavior and pressure-induced configurations transitions of CL-20 at atomistic scale.

中文翻译：

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来自密度泛函理论计算的高能 ε-CL-20 晶体的压缩行为

使用色散校正密度泛函理论，我们全面探索了六硝基六氮杂异武兹烷 (CL-20) 晶体在静水压和单轴压缩下的结构和拉曼光谱。通过静压压缩，我们验证了 PBE-D2 方案可以准确描述零压力和高压下的晶体结构。沿着不同的取向压缩，CL-20 晶体在主应力和剪切应力方面表现出相当大的各向异性。进一步分析了压缩对 CL-20 振动特性的影响。沿 [100] 方向的压缩会引起硝基振动模式的一些异常变化，这与硝基空间方向的变化有关。