Solid State Nuclear Magnetic Resonance ( IF 3.2 ) Pub Date : 2019-11-21 , DOI: 10.1016/j.ssnmr.2019.101638 Laura Martel 1 , Attila Kovács 1 , Karin Popa 1 , Damien Bregiroux 2 , Thibault Charpentier 3
We present the study of the phosphorus local environment by using 31P MAS NMR in a series of seven double monophosphates MIIMIV(PO4)2 (MII and MIV being divalent and tetravalent cations, respectively) of yavapaiite and low-yavapaiite type crystal structures. Solid-state and cluster DFT calculations were found to be efficient for predicting the 31P isotropic chemical shift and chemical shift anisotropy. To achieve this performance, however, a proper computational optimisation of the experimental structural data was required. From the three optimisation methods tested, the full optimisation provided the best reference structure for the calculation of the NMR parameters of the studied phosphates. Also, a better prediction of the chemical shifts was possible by using a correction to the GIPAW calculated shielding.
中文翻译:
结晶磷酸盐基质的31 P MAS NMR和DFT研究
我们使用31 P MAS NMR对Yavapaiite和低价磷矿的七个七个双单磷酸盐M II M IV(PO 4)2(M II和M IV分别为二价和四价阳离子)系列进行磷环境研究。亚瓦派特型晶体结构。发现固态和群集DFT计算对于预测31P各向同性化学位移和化学位移各向异性。但是,要实现这一性能,需要对实验结构数据进行适当的计算优化。从测试的三种优化方法中,全面优化为计算所研究磷酸盐的NMR参数提供了最佳参考结构。此外,通过对GIPAW计算得出的屏蔽值进行校正,可以更好地预测化学位移。