An Imbalance in the Force: The Need for Standardised Benchmarks for Molecular Simulation

Force fields (FF) for molecular simulation have been under development for more than half a century. As with any predictive model, rigorous testing and comparisons of models critically depends on the availability of standardized datasets and benchmarks. While such benchmarks are rather common in the fields of quantum chemistry, this is not the case for empirical FFs. That is, few benchmarks are re-used to evaluate FFs and development teams rather use their own test sets. Here we present an overview of currently available tests and benchmarks for computational chemistry, focusing on organic compounds, including halogens and common ions, as FFs for these are the most common ones. We argue that many of the benchmark datasets from quantum chemistry can in fact be re-used for evaluating FFs, but new gas phase data is still needed for compounds containing phosphor and sulfur. In addition, more non- equilibrium energies and forces are needed for compounds with halogens, P and S. For the condensed phases there is a large body of experimental data available and tools to utilise these data in an automated fashion are under development. If FF developers, as well as researchers in artificial intelligence would adopt a number of these datasets it would become easier to compare the relative strengths and weaknesses of different models and to, eventually, restore the balance in the force.