Studying the formation and stability of molecular clusters has been of interest in many scientific domains, such as atmospheric chemistry, 1-6 biology, 7,8 astronomy, and material science. A particularly illustrative example is the study of molecular clusters formed in the atmosphere via gas-to-particle conversion, which is the first step in the formation of secondary atmospheric aerosol particles. Once formed, these aerosols have a significant impact on climate and air quality, and thus also human health. Molecular clusters can be experimentally detected, but cluster observations are generally complicated due to a variety of issues such as the typically very low concentrations (often below the detection limit of instruments), the changes cluster undergoes inside the instruments, and clusters being too small to detect. Many key properties strongly depend on the cluster configuration, which is a priori unknown and very seldom directly measurable. Hence, computational chemistry is an important additional tool to study clusters.