Energy levels obtained with respect to different reference geometries differ exactly by the energy differences of these geometries so that there is no effect in total. Still, there are two further effects that cause differences. First, obtaining the curvature for the cancellation harmonic oscillator at a different location can give different results. For the ethanol monomer, the wavenumber is lowered by 10 %, lowering the zero-point energy by only about 0.17 kJ mol -1 . Second, using a different reference geometry with different normal modes of course affects total zero-point vibrational energies (ZPVEs) and thermochemical results. For the ethanol monomer, this difference makes up 0.27 kJ mol -1 . Altogether, in this example, the choice of reference geometry effects zero-point energies far below chemical accuracy. It can be expected that these effects are substantially larger for HRs that link hydrogen-bonded and non-hydrogen-bonded conformations. Modeling thermochemistry, i.e. enthalpy and entropy as functions of temperature, is affected by the HiFi updates and the MuFi model for this HR. Here, the number of minima and also their approximate shape is unchanged from LoFi to HiFi, but the two non-planar minima are lifted by about 0.9 kJ mol -1 , cf. Fig. . While entropy barely changes (by only 0.01 J mol -1 K -1 ), the enthalpy and accordingly free energy raise by about 0.6 kJ mol -1 .