Molecular mechanics calculations, based on equations such as the one below, are used to investigate a colorectal cancer drug, 5-fluorouracil, intercalated into a clay, montmorillonite. This combination is currently being considered as a drug delivery system. The swelling of clays has been studied since the 1930s and is still not fully understood. Spartan ’14 is used for the calculations. Semi-empirical and ab initio basis set scaling is also examined since there are roughly 300 atoms involved in the full model.