As fitting algorithm, a radial-basis-function (Rbf) interpolator was used with multiquadric basis functions. The width of the multiquadric function was chosen to be ε = 1.0. The root-mean-square-deviations (RMSD) is used here to indicate whether the training set and interpolation algorithm is capable to reproduce the desired observables. The RMSD of the energy and gradients for the model are 5.9 meV and 11 meV, respectively, which confirmed the validity of the employed scheme. Fig. shows the PE surfaces as functions of time of a representative validation trajectory (solid) together with the predictions of the interpolator (dashed). From the figure it is hard to see any difference as the curves lie on top of each other, reflecting their excellent agreements.