Rayón and Sordo plot their PESs data only on a qualitative scale, but this can well serve to demonstrate the MuFi treatment. Normalised results for the tetrahydrofuran example using the Matern32 kernel using qualitative results by Rayón and Sordo at MP2/cc-pvdz (blue dots) and MP2/aug-ccpvtz (black dots and dashed black line) levels of theory. Line and color code is the same as in Fig. ; the standard deviation is visualised as a shadow.