Crystal Structure Prediction of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) by a Tailor-Made OPLS-AA Force Field
Crystal Structure Prediction of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) by a Tailor-Made OPLS-AA Force Field
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DOI：
10.1021/acs.cgd.1c00208
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发表时间：
2021-04-16
影响因子：
3.8
通讯作者：
Xue, Xianggui
中科院分区：
文献类型：
--
作者：
Wang, Chaoyu;Ni, Yuxiang;Xue, Xianggui
Predicting the crystal structure of an energetic compound is an important aspect of energetic crystal engineering because an accurate crystal structure prediction (CSP) presents a base for accurately predicting almost all properties and performances. Therein, a sufficiently accurate intermolecular force field is required. In this work, a tailor-made OPLS-AA force field (TM OPLS-AA FF) for the 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) molecule is refitted based on quantum chemical calculations with a dispersion-corrected density functional M06-2X. Based on the FF, all of the three experimentally observed polymorphs of CL-20, epsilon-, beta- and gamma-formed CL-20, are accurately predicted as ranked 2, 1, and 1 in the energy landscapes, respectively. Meanwhile, the geometric packing similarity check exhibits a small deviation of the prediction from the experimental. Moreover, many thermodynamically feasible crystal structures with densities >2.0 g/cm(3), even as high as 2.099 g/cm(3), are ascertained on the energy landscapes, providing a useful complement to experimental screening for the possible polymorphs. All these validate the FF. This work is expected to pave a wave to reveal the mechanisms of the polymorphic and morphologic control and transition of CL-20.
