The polarized electrostatic interaction ∆G elst is a key factor in determining amino acide residues interact with their surroundings, which is essential for understanding protein stability in biological environments. Table compares ∆G elst for the three forms of each protein (acid, base, and imidazolium-flipped acid), computed using different PCM-based boundary conditions. We now understand that absolute HetPCM solvation energies do not always agree with Poisson benchmarks, and there is significant variation in ∆G elst across different solvation models in Table . The isotropic PCM affords the largest values of |∆G elst |, because it allows the most polarization charge to accumulate at the solute cavity surface.