化学
化学位移
分子间力
密度泛函理论
氢键
基准集
晶体结构预测
结晶学
晶体结构
分子
Crystal(编程语言)
烟酰胺
计算化学
物理化学
有机化学
酶
程序设计语言
计算机科学
作者
Dmytro Dudenko,Jonathan R. Yates,Kenneth David Maclean Harris,Steven P. Brown
出处
期刊:CrystEngComm
[The Royal Society of Chemistry]
日期:2013-01-01
卷期号:15 (43): 8797-8797
被引量:72
摘要
Density functional theory (DFT) calculations using the Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional are presented for a 1 : 1 cocrystal formed by indomethacin and nicotinamide (IND-NIC) as well as for crystal structures of the individual components. DFT-D approaches which correct the DFT energy for dispersion effects, specifically the Grimme (G06) and Tkatchenko–Scheffler (TS) schemes, are investigated: for geometry optimisation starting with crystal structures determined experimentally by diffraction and allowing the atomic positions and the unit cell to vary, closest agreement with the experimental unit cell parameters is achieved with the PBE-TS approach (calculated volumes are less than 4% smaller than in experiment). Calculations of solid-state NMR chemical shifts using the GIPAW (gauge including projector augmented wave) approach are presented. Closest agreement between NMR chemical shifts calculated with variable and fixed (experimental) unit cell parameters is also observed for the PBE-TS approach: the root mean squared standard deviation difference is 0.15 ppm (1H) and 0.29 ppm (13C) for PBE-TS, as compared to 0.45 ppm (1H) and 0.68 ppm (13C) with standard PBE. Differences in 1H chemical shifts calculated for the full periodic crystal structure and for isolated molecules extracted from the geometry-optimised crystal structure are presented in conjunction with NICS (nucleus independent chemical shift) maps, so as to separately quantify intermolecular hydrogen bonding and π–π interactions. This analysis is complemented by total energy calculations, including also at the B97D/6-311+G* level of theory with basis set superposition error correction, in order to understand the interactions that drive cocrystallisation.
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