Grand challenges in quantum-classical modeling of molecule-surface interactions

A detailed understanding of the adsorption of small molecules or macromolecules to a materials surface is of importance, for example, in the context of material and biomaterial research. Classical atomistic simulations in principle provide microscopic insight in the complex entropic and enthalpic interplay at the interface. However, an application of classical atomistic simulation techniques to such interface systems is a nontrivial problem, mostly because commonly used force fields cannot be straightforwardly applied, as they are usually developed to reproduce bulk properties of either solids or liquids but not the interfacial region between two phases. Therefore, a dual-scale modeling approach has often been the method of choice in the past, in which the classical force field is parameterized such that quantum chemical information on near-surface conformations and adsorption energies is reproduced by the classical force field. We will discuss in this review the current state-of-the-art of quantum-classical modeling of molecule-surface interactions and outline the major challenges in this field. In this context, we will, among other things, lay emphasis on discussing ways to obtain representable force fields and propose systematic and system-independent strategies to optimize the quantum-classical fitting procedure.