tent charge (de)localization in the n-body calculations for charged fragments. To obtain a polarization environment that is comparable to that of the supersystem, high-order n-body calculations are required, beyond n = 4. Alternatively, dielectric boundary conditions provide a simple and low-cost means to mimic this polarization. In principle, one might consider the use of heterogeneous dielectric boundaries, such that hydrophobic parts of the protein are treated differently from solvent-exposed portions. This has not been pursued in the present work, where we simply aim to demonstrate that convergence of the MBE in vacuo is not well-defined.