Abstract The structural, vibrational and thermodynamic properties of the cyanuric triazide crystal is investigated through density functional theory (DFT) simulations within the dispersion corrected generalized gradient approximation (GGA + G06) by considering the norm conserving pseudopotentials. Infrared spectra and Born effective charges are computed through linear response method using the density functional perturbation theory (DFPT). The experimentally observed vibrational modes are well reproduced in our calculations. The high intensity infrared absorption bands in the range of 1200–1500 cm−1 originate from the vibrations of the N 3 group. The Born effective charges indicate that the compound to be asymmetric. The calculated phonon dispersion curve clearly show the absence of imaginary frequencies along the high symmetry directions, which confirms the dynamical stability of C 3 N12, and the interaction between the acoustic and low lying optical modes results in enhanced phonon scattering enabling low thermal conductivity in this compound. The phonon partial density of states reveals that the low-frequency regions (below 500 cm−1) are dominated by N atoms. In addition, the compound shows covalent nature owing to the hybridization between C and N atoms. The phonon spectra and thermodynamic properties of C 3 N12 were computed for the first time, which still awaits experimental confirmation. The temperature-dependent heat capacity and Debye temperature has been discussed in detail. The heat capacity C V of C 3 N12 increases with temperature, being 98.13 cal/cell.K for T = 306 K. Finally, the entropy, enthalpy and Helmholtz free energy, are investigated and discussed in the framework of the harmonic approximation. From the above results, it can be inferred that cyanuric triazide is an effective initiating explosive, as it possess low-thermal conductivity.

中文翻译：

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含能固体三聚氰脲晶格动力学和热力学性质的计算研究

摘要 在色散校正广义梯度近似 (GGA + G06) 中，通过考虑范数守恒赝势，通过密度泛函理论 (DFT) 模拟研究了氰尿酸三叠氮化物晶体的结构、振动和热力学性质。使用密度泛函微扰理论 (DFPT) 通过线性响应方法计算红外光谱和波恩有效电荷。实验观察到的振动模式在我们的计算中得到了很好的再现。1200-1500 cm-1 范围内的高强度红外吸收带源于N 3 基团的振动。Born 有效电荷表明该化合物是不对称的。计算出的声子色散曲线清楚地表明沿高对称方向没有虚频，这证实了 C 3 N12 的动态稳定性，声学模式和低位光学模式之间的相互作用导致声子散射增强，从而使该化合物的热导率较低。声子部分态密度表明低频区域（低于 500 cm-1）由 N 原子主导。此外，由于 C 和 N 原子之间的杂化，该化合物表现出共价性质。首次计算了C 3 N12 的声子谱和热力学性质，仍有待实验证实。已经详细讨论了与温度相关的热容和德拜温度。C 3 N12 的热容 CV 随温度升高而增加，T = 306 K 时为 98.13 cal/cell.K。最后，熵、焓和亥姆霍兹自由能，在调和近似的框架内进行研究和讨论。由以上结果可以推断出，三叠氮化三聚氰脲具有低热导率，是一种有效的起爆炸药。