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摘要
High pressure Raman experiment was performed to compare RDX and HMX crystals. Ab initio calculations using B3LYP Density Functional Theory method with Sadlej's medium-sized polarized basis set (SadlejpVTZ) were carried out for Caae RDX and 1,5-diaxial-3,7-diequatorial chair HMX molecules. Our calculations and measured Raman vibrational spectra reveal both molecules have similarities on bonding and vibrational properties at ambient pressure. However, high pressure responses for both molecules aren't the same. For RDX, at pressure near 4 GPa, a number of changes become apparent in the Raman spectra, such as modes splitting, intensity modification, and discontinuity of pressure-dependence of frequency shifts, which are consistent with previous experiment and believed to associate with alpha-gamma phase transition. For HMX, only slight conformational deformation involving NO2 group was observed, and was considered as an onset of beta-epsilon phase transition. It is proposed that the markedly different behavior under high pressure for these two molecules results from different molecular packing in unit cell.
- 出版日期2016-9-5
- 单位哈尔滨工业大学; 中国工程物理研究院流体物理研究所; 中国工程物理研究院
