Crystal Morphology Prediction with Dispersion Corrected Density Functional Theory

This thesis investigates the application of dispersion corrected density functional theory to the problem of crystal morphology prediction. A many body dispersion correction scheme is selected based on its accuracy in reproducing the energies and geometries of benchmark sets of molecular dimers and molecular crystals. This scheme is subsequently used to rank the energies of pairs of polymorphs, demonstrating that the consistency of errors is suffcient for the calculation of relative growth rates of crystal faces. The scheme is successfully applied to the determination of low energy gas phase conformations of biphenyl and paracetamol demonstrating that it is applicable to calculations on isolated molecules that would be required for more sophisticated morphology prediction methods. Finally, the scheme is used to calculate attachment energies of crystallographic forms of biphenyl, anthracene, cytosine, and paracetamol. The calculated attachment energies are used to generate growth morphologies of these crystals and compared with morphologies determined with other methods, and observed morphologies where available. This work demonstrates that dispersion corrected density functional theory is suitable as a calculation engine for crystal morphology prediction. However, increasing the level of theory in this way will not always improve predictions as inaccuracies are due to other factors effecting crystal growth that are not captured by the attachment energy model.