CrystalExplorer: a tool for displaying Hirshfeld surfaces and visualising intermolecular interactions in molecular crystals

Crystal structure prediction on the basis of just the chemical formula has long been considered a formidable or even insoluble problem. Being able to solve this problem would open the possibilities to find new phases of planetary materials at extreme conditions [1,2], to solve structures where experimental data are insufficient, and to design new materials entirely on the computer (once the structure is known, it is relatively easy to predict many of its properties -e.g., Essentially, the problem can be reduced to the problem of global optimization of the free energy of a crystal with respect to structural parameters. Recently, we addressed this problem and devised a new method based on a specifically devised and carefully tuned ab initio evolutionary algorithm, which we implemented in the USPEX code (Universal Structure Predictor: Evolutionary Xtallography, At given P-T conditions, USPEX finds the stable structure and a number of robust metastable structures. USPEX uses ab initio free energy as evaluation function and features local optimization and spatial heredity, as well as further operators such as mutation and permutation. This method has been widely tested and applied to solve a number of important problems. It turns out to be extremely efficient for predicting crystal structures with very different geometrical features and types of chemical bonding. In this talk I will discuss some of the applications of this method to a number of interesting materials (C, N, O, S, H 2 O, MgSiO 3 , CaCO 3 , MgCO 3 ). Possible industrial applications will be discussed as well. Future developments of the method will be outlined.