On page 877 (DOI: 10.1002/jcc.24234) Hongbo Du and Xianghong Qian use a QM/MD method to investigate the hydration properties of carboxybetaine zwitterion brushes with varying separation distances between the quaternary ammonium cation and carboxylic anion. The brushes consist of zwitterion trimers in order to mimic interacting zwitterion chains grafted on a substrate as well as polymers with interacting zwitterion side chains. The value of the charge, the separation distance, and chain interactions play a critical role in the hydration properties of the zwitterions.