This talk will be given by Professor Greg Beran Department of Chemistry, University of California Riverside, USA on the topic of “Overcoming the limitations of density functional theory for crystal structure prediction of pharmaceuticals and materials.”

The talk will be in the Sargent Centre seminar room RODH 617, 11-12, with refreshments served 10.30-11

Abstract

Organic crystal structure prediction has become increasingly useful for solid-form screening in the pharmaceutical industry and for crystal engineering of new organic materials.  Much of this success stems from the often high-accuracy provided by van der Waals-inclusive density functional theory (DFT) models.  However, while those models often work well, they exhibit serious, systematic failures for certain classes of systems, such as some types of conformational polymorphs.  In the first part of the talk, we will discuss the origin of this failure and a computationally practical route for overcoming it, with examples ranging from pharmaceuticals to organic semi-conductor materials.  The second half of the talk will focus on organic photomechanical crystals, which are a promising class of materials that transform light into mechanical work, with work densities that are much higher than piezoelectrics or many polymer materials.  However, understanding the solid-state photochemical transformations that produce the mechanical work has proved challenging experimentally.  We will present a theoretical framework that maps from molecule to crystal, which predicts the photochemically-driven solid-state transformation and the associated mechanical response, and which establishes a thermodynamic cycle for computing the work produced by the photomechanical engine.