The Calculation of the Diamagnetic Susceptibility Tensors of Organic Crystals: from Coronene to Pharmaceutical Polymorphs

Understanding why crystallization in strong magnetic fields can lead to new polymorphs requires methods to calculate the diamagnetic response of organic molecular crystals. We develop the calculation of the macroscopic diamagnetic susceptibility tensor, χcryst, for organic molecular crystals using periodic density functional methods. The crystal magnetic susceptibility tensor, χcryst, for all experimentally known polymorphs, and its molecular counterpart, χmol, are calculated for flexible pharmaceuticals such as carbamazepine, flufenamic acid and chalcones, and rigid molecules, like benzene, pyridine, acridine, anthracene and coronene, whose molecular magnetic properties have been traditionally studied. A tensor addition method is developed to approximate the crystal diamagnetic susceptibility tensor, χcryst, from the molecular one, χmol, giving good agreement with those calculated directly using the more costly periodic density functional method for χcryst. The response of pharmaceutical molecules and cr...