In this study, we first estimated the total energy drift of the cAMP and ethane systems at six different time steps: 0.5, 1.0, 2.0, 2.5, 3.333, and 4.0 femtoseconds (fs). Simulations were conducted for both the ligand in water and the protein-ligand complex in water. Additionally, dU dλ was assessed under four different conditions: (i) SHAKE constraints for hydrogen atoms with Hydrogen Mass Repartitioning (HMR) applied to both the ligand and the protein-ligand complex, (ii) SHAKE constraints for hydrogen atoms without HMR for both the ligand and protein-ligand complex, (iii) no SHAKE constraints for hydrogen atoms with HMR applicable to both the ligand and protein-ligand complex, and (iv) no SHAKE constraints and no HMR applied to either the ligand or the protein-ligand complex. In total, 120 simulations were performed for each run.