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分子晶体的多晶问题对于生命科学的重要性日益突出,因而吸引了广泛的关注.但是,对于含分子数较多的分子晶体的研究,尤其是其振动光谱的研究,使用传统的周期性量子化学方法并不是非常有效.本文使用周期性的基于能量的分块方法研究了吡嗪酰胺多晶的晶体结构与振动光谱.通过X光衍射结构与理论预测的结构进行对比发现,对于该晶体,PBC-D3泛函是整体表现最出色的泛函.使用该泛函所计算得到的振动光谱也与实验得到的光谱有比较高的吻合.此外,通过理论与实验的振动光谱的比照得出,吡嗪酰胺晶体的?相存在某种无序结构,该结果与之前的实验观测相互印证.
The polycrystalline problem of molecular crystal is becoming more and more important to life science and attracts a lot of attention.However, the research on the molecular crystal with more molecule, especially its vibrational spectrum, uses the traditional periodic quantum Chemical method is not very effective.In this paper, the periodic energy-based block method was used to study the crystal structure and vibrational spectra of pyrazinamide polycrystal.Comparing X-ray diffraction structure and theoretical prediction structure, we found that for this crystal, The PBC-D3 functional is the best overall functional, and the vibrational spectrum calculated by this functional is in good agreement with the experimental spectra.Furthermore, through the comparison of the theoretical and experimental vibrational spectra, Pyrazinamide crystal phase there is some disordered structure, the results of the previous experimental observations confirm each other.