Abstract by Luther Wang
Chemistry and Biochemistry
Thermal Ellipsoids for NMR Crystallography
his work describes a computational method that calculates the uncertainties in the positions of a crystal, commonly called the B factor. Currently the B factors in the Cambridge database is assumed to be the same in all directions, and they are very large due to the sparse coverage of electron density in certain areas. Using NMR tensor data, the first paper uses a Monte Carlo sampling approach to generate an ensemble of structures. Then these structures are processed using a DFT program to obtain their chemical shielding tensors. Finally, the program removes all sampled structures that lies outside the one standard deviation of the average. The second paper provides a new visual tool to visualize this B factor by plotting the tensors so that the volume of the uncertainties can be seen.