We employed the Clusteromics I-V datasets for the benchmark. These datasets consist of clusters of the type (acid) 1-2 (base) 1-2 and includes mixtures of different acids (SA, MSA, FA, and NTA) and bases (AM, MA, DMA, TMA, and EDA). Overall, the Clusteromics I-V datasets contain up to 56,436 cluster structures optimized at the ωB97X-D/6-31++G(d,p) level of theory. This is an insurmountable number of clusters to further optimize at the MP2 level. Hence, we have chosen to only use the 5 lowest energy structures for each cluster composition, which in total yields a dataset of 1283 cluster structures.