The terms in Eq. 4 have the same meaning as in Eq. 3 save that ∆F AA refers to the force residual between the IBI calculated force and the atomistically sampled force (∆F AA = F AA -F IBI CG )and ∆F ML CG is the NN prediction of the residual. To calculate the ∆F AA residuals, the corresponding low-level models (IBI PC or IBI PC ) were trained beforehand as described in the previous section.