The disulfide-bonded cysteine used in addition a thiomethyl capping group to represent a disulfide-bonded cysteine neighbor. In order to also develop parameters for both charged and neutral N-and C-terminals, a set of structures were also generated with only one capping group being either acetyl and N-methyl, but having the other capping group being either a protonated amino (Fig. ), carboxylate (Fig. ), amine (Fig. ), or carboxylic acid (Fig. ) group. The geometries of the generated structures were optimized with the HF-3c method as implemented in the ORCA program, with the dihedral angles constrained to the values obtained from the rotamer library. The geometry optimizations include an implicit water environment, modeled with the C-PCM, in order to avoid any internal hydrogen transfers.