Calculation of NMR chemical shifts in organic solids: Accountingfor motional effects

摘要

NMR chemical shifts were calculated from first principles for well defined crystalline organic solids.These density functional theory calculations were carried out within the plane-wave pseudopotentialframework, in which truly extended systems are implicitly considered. The influence of motionaleffects was assessed by averaging over vibrational modes or over snapshots taken from ab initiomolecular dynamics simulations. It is observed that the zero-point correction to chemical shifts canbe significant, and that thermal effects are particularly noticeable for shielding anisotropies and fora temperature-dependent chemical shift. This study provides insight into the development of highlyaccurate first principles calculations of chemical shifts in solids, highlighting the role of motionaleffects on well defined systems.