Structure Prediction of Organic/Inorganic Interfaces with Genarris

Organic/inorganic interfaces perform critical functions in organic electronic devices and their structure can affect device performance. In addition, interactions with the substrate can promote the growth of otherwise metastable thin film structures by epitaxial templating. Predicting the structure of organic/inorganic interfaces by computer simulations can aid the design of interfaces with desirable properties. We present Genarris Interfaces, a structure generator of organic/inorganic interfaces. Genarris uses epitaxy matrices to impose commensurism with the substrate. Film structures are generated in all layer groups compatible with the substrate symmetry and the number of molecules per unit cell. Clustering and down-selection are performed to reduce the number of structures while maintaining diversity of packing motifs. Finally, relaxation and stability ranking are performed using dispersion-inclusive density functional theory (DFT). We demonstrate the application of Genarris for the interfaces of PTCDA/Ag(111), TCNE/Au(111), and naphthalene/Cu(111). In all cases, we find generated structures that resemble experimental scanning tunneling microscopy (STM) images. The electronic structure agrees well with spectroscopy data, where available. Genarris Interfaces can be used to predict the structure of organic/inorganic interfaces, to generate initial populations for other structure prediction algorithms, and to generate datasets for training machine learning models.