Theoretical study of the hydrolysis of ethyl benzoate in acidic aqueous solution using the QM/MC/FEP method

► We investigated the hydrolysis of ethyl benzoate by the QM/MC/FEP method. ► The diffuse functions affected directly on geometries and energies of calculation. ► The model including 2 waters (2W) cannot represent the mechanism of the hydrolysis. ► The 3rd water molecule (3W model) is necessary and its position is very important. ► The ΔG‡ value of 3W model is consistent with the experiment within 1.0 kcal mol−1.