For all investigated configurations and MTPs, MD simulations are propagated for 1 ns, which yields converged averaged quantities as explicitly demonstrated for the "gap" in Figure . Further, we also ensured energetic convergence, as shown in Figure , where most of the drift in total energy is less than 0.5 meV/(ns•atom). To quantitatively evaluate the liquid "gap", a Gaussian-shaped spherical electron density of width σGAUSS is assigned to each atomic position to subsequently transform the trajectory data into a time and laterally averaged electron density profile along the surface normal that is directly comparable to the experimentally obtained density shown in Figure . The Gr-Cu "gap" is then determined by the analog Cu inflection-point measure used in the experimental analysis. As detailed in the SI and Figure , the thus determined value is essentially insensitive to the Gaussian width employed in the construction of the electron density. In this work, we call this definition of gap the inflectionpoint "gap" and adhere to it for all "gap" value evaluations. Furthermore, since the surface atoms' positions can be well defined for a solid slab, a direct method for the Gr-Cu "gap" is also evaluated in the SI. This value is usually determined for solid substrates in experiments . As evaluated in our simulations (see SI), we can translate between these two "gap" definitions by a constant offset of 𝛿𝐷=1 Å to compare "gaps" on solid and liquid Cu. All the details on the evaluation of properties and their uncertainties are shown in the SI. Graphene Adsorption Height. Figure compares the experimental and computed electron density profiles of the liquid Cu surface covered with a Gr sheet at the same temperature of 1370K. Specifically, we compare the computed density obtained with the MTP@PBE+MBD potential, i.e., the MTP trained on the DFT data calculated with the PBE functional and MBD dispersion correction. The two curves are in essentially perfect quantitative agreement. The slightly higher bulk plateau of the experimental curve reflects the slightly underestimated liquid Cu density of DFT PBE+MBD (see below). On top of this, the computed density profile exhibits some minor oscillations near the Cu surface region (z ~ -3-4 Å), which indicate some residual surface layering (compare to the atomic density profile in Figure ). This would not be untypical for liquid metals, but is not detected in the experimental spectra. We stress that the present MD simulations cannot capture macroscopic effects like capillary waves, which, however, are detectable in the experiment. We correspondingly believe that a resulting averaging effect of capillary waves may explain the absence of such oscillations in the experimental profile.