There is a major difference between the current glutamic acid-glutamate complex and the previous phenol-water complex: for the phenol-water complex, the hydrogen bond distance and the O•••O distance shorten in aqueous phase, whereas for the glutamic acid-glutamate complex, these distances barely change with CNEO-DFT or even becomes slightly longer with DFT. This phenomenon has been observed in the past and it was attributed to the differences between neutral complexes and negatively charged complexes. Heuristically speaking, the attractive interactions between the solvent and solute compress the solute and thereby shorten the hydrogen bonds, as observed in neutral complexes. However, in charged complexes, the dipole-ion interactions are much stronger than the dipole-dipole interactions present in neutral complexes. Consequently, the hydrogen bonds in charged complexes are already much shorter in the gas phase, and placing the charged complex in a polar solvent makes little difference to the hydrogen bond length. However, more rigorously, the bond length changes reflect an interplay between electronic effects, nuclear quantum effects, and solvation