The first test problem (TP1) is typical of the size of problem investigated by other authors. This involves fitting 6 model parameters for the set of interactions between carbon and hydrogen. Only one reference dataset is included in this fitting, containing 18 structures and 1,380 residuals. Thereafter, the test problems grow in size as more species, containing a wider range of atom types, are added to the training. With each additional atom type, the number of fitting parameters increases nonlinearly since cross-interactions are also parameterized. TP2 is already larger than most problems that have been investigated in the literature, both in terms of the number of parameters that are simultaneously estimated and the number of training structures/data points. The largest test problem is TP7, which includes all of the primary reference datasets developed in this work and involves fitting 62 model parameters simultaneously. In this final problem, all 445 structures are included in the fitting resulting in 28,465 residuals. It is important to note that each test problem is solved as an independent parameter estimation, without carrying forward any parameters obtained from preceding tests.