For CPCM calculations, the solute cavity was built using defaults available in TeraChem (i.e., 1.2 times Bondi's van der Waals radii). The relative dielectric constant of the solvent, ε, was varied from 1 (gas-phase) to 80 (water), with values taken at 1, 2, 4, 10, and 80 for all the 25 peptides, because the CPCM field strength is proportional to The performance of PCM in improving SCF convergence was compared to the widely used level-shifting technique. The level-shifting value for each peptide was set as the difference of HOMO-LUMO gaps calculated in aqueous solvation (ε=80) and the gas phase.