Abstract

The exchange-hole dipole moment (XDM) method is a density-functional model of London dispersion based upon second-order perturbation theory. The XDM dispersion coefficients are non-empirical and depend directly on the electron density and related properties, allowing variation of the atomic dispersion coefficients with changing chemical environment. XDM offers simultaneous high accuracy for a diverse range of chemical systems, such as intermolecular complexes, layered materials, surface adsorption, and molecular crystals. In this talk, recent applications of XDM will be presented, with a focus on the use of low-cost and composite approaches for molecular crystal-structure prediction (CSP). In particular, the application of composite methods to chiral helicenes, which have applications in organic electronics, and to four pharmaceutical compounds: 5-fluorouracil, naproxen, carbamanzapine, and olanzapine, will be illustrated. Finally, the effect of the density-functional delocalisation error on CSP is highlighted for organic acid-base co-crystals.