OPTICS: Operant Probability Theory in Crystal Solutions, Application of ssNMR, and Probability Theory in Polymorph Identification
Gabriel A. Valdivia‐Berroeta, Kanika Sarpal, Nina C. Gonnella
Abstract
A robust method using 13C ssNMR data for accurate distinction and identification of crystalline polymorphs is described. Quantum chemistry and density functional theory (QM/DFT) combined with Bayesian probability theory enables accurate identification and distinction among different polymorphs with similar ssNMR spectra. The gauge including the projector-augmented wave (GIPAW) method is used in calculating the 13C ssNMR chemical shifts. A linear scaling reference term for 13C ssNMR is determined that improves the accuracy of the calculated chemical shifts. Statistical distribution of predicted chemical shifts from a set of 59 solid forms shows deviations from experiment with a range of ±6.2 ppm for 13C. The process enables accurate solid form identification of either experimental or predicted crystal structures by comparison with 13C ssNMR experimental data. This method has been applied to select the correct polymorph from a set of predicted crystal structures.