Department of Chemistry, Faculty of Science, and Center for Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University , Phyathai Road, Pathumwan, Bangkok 10330, Thailand.
J Phys Chem A. 2012 Aug 2;116(30):8092-9. doi: 10.1021/jp304858y. Epub 2012 Jul 20.
Multitemperature synchrotron diffraction data to 0.5 Å resolution in the temperature range 10-298 K and neutron data at 18 K of the α-glycine polymorph have been collected at the KEK photon factory (PF), SPring-8 and the Institut Laue Langevin (ILL) for the study of molecular motion in the crystal and of the associated thermodynamic functions. Atomic displacement parameters (ADPs) of non-H atoms are obtained from refinements based on nonspherical atomic scattering factors (invariom model) to minimize correlation between parameters describing thermal motion and valence electron density. The ADPs in the temperature range 50-298 K from SPring-8 connect smoothly with those from neutron diffraction at 18 K and 288-323 K. The combined ADPs from both sources covering the temperature range 18-323 K are used for a normal-mode analysis in the molecular mean field approximation. The lattice vibration frequencies from the ADP analysis and the internal vibration frequencies from an ONIOM (B3LYP/6-311+G(2d,p):PM3) calculation together with the Einstein, Debye, and Nernst-Lindemann models of heat capacity are used to calculate Cp, Hvib, and Svib values that are in good agreement with those from calorimetry.
已在 KEK 光子工厂 (PF)、SPring-8 和法国格勒诺布尔的伊莱娜·若贝尔中子研究所以及德国的马克斯·普朗克研究所收集了α-甘氨酸多晶型物在 10-298 K 温度范围内的多温度同步辐射衍射数据和 18 K 时的中子数据，以研究晶体中的分子运动和相关热力学函数。非氢原子的原子位移参数 (ADP) 是通过基于非球形原子散射因子的细化（不变模型）获得的，以最小化描述热运动和价电子密度的参数之间的相关性。来自 SPring-8 的 50-298 K 温度范围内的 ADP 与来自 18 K 和 288-323 K 时的中子衍射的 ADP 平滑连接。来自两种来源的组合 ADP 涵盖了 18-323 K 的温度范围，用于分子平均场近似下的正则模态分析。从 ADP 分析得出的晶格振动频率和 ONIOM（B3LYP/6-311+G(2d,p)：PM3）计算的内部振动频率与爱因斯坦、德拜和能斯特-林德曼热容模型一起用于计算 Cp、Hvib 和 Svib 值，这些值与量热法的值非常吻合。
