For CG particles containing more than one heavy atom, we found that the EX2 method provided the most accurate estimation of effective volumes, while the EX1 and AEX methods tended to lead to overestimation. Using the 𝛔 parameters derived with EX2 method, the 𝝐 parameters were further obtained through minimizing the error function in eq.( ). This approach is referred to as EX2-rematch method.