We calculate AHFEs for 2 sets of AmberTools AM1-BCC partial charges generated from the exact same input conformer but di erent hardware. We find that in most cases, partial charges generated from di erent hardware yielded similar AHFE values within 1 kcal/mol of each other (Figure ). However, we observe maximal partial charge di erences of 0.09 e resulting in a 3.8 ± 0.1 kcal/mol di erence in calculated AHFE, which is a rather large discrepancy and one which is certainly significant for practitioners.