The octamer structures were also extracted from the bulk (1024 molecules) PIMD simulations at ambient condition. The octamer test is designed to check the model performance in bulk-like geometries, while their performance for cluster-like geometries were examined using hexamer and 12mer test. In this test, eight most stable hexamers and seven most stable 12mers were selected, and their interaction energies were computed and used as benchmark data. The structures of the hexamers and 12mers were optimized at MP2/AVDZ level of theory, with monomer geometries fixed at equilibrium geometry.