Keynote
UNDERSTANDING MOLECULAR CRYSTALS FROM FIRST PRINCIPLES

Molecular crystals are crystalline solids composed of molecules bound together by relatively weak intermolecular interactions, typically consisting of van der Waals (vdW) forces and/or hydrogen bonds. Such crystals play an important role in many areas of science, ranging from mechanics and electronics to biology and medicine. Therefore, a large amount of effort has been dedicated to understanding their structure and properties

Prediction of structural, mechanical, electronic, and optical properties of such materials from first principles is highly desired for understanding their unique properties and for allowing rational design of novel materials and structures. Preferably, we would like to predict such quantities using density functional theory (DFT), because the relative computational simplicity afforded by DFT allows us to attack realistic problems. Unfortunately, despite many other successes, DFT has traditionally struggled with prediction of the above quantities.

Here, I will present novel approaches that overcome these difficulties quantitatively. I will show, using many practical examples, how we have used these new methods to predict a variety of unusual and often unexpected structural motifs, mechanical properties, electronic behavior, and optical effects in a large range of naturally-occurring and synthetic molecular crystals, based on amino-acids, nucleic acids, aromatic molecules, metal-organic molecules, and more.