All calculations were performed using the Gaussian software suite . Density functional theory (DFT) was used for the calculations of energy and harmonic vibrational wavenumbers . B3LYP was used as a functional of choice together with the aug-cc-pVDZ basis set . The aug-cc-pVDZ-PP basis set was chosen for silver atoms, introducing the scalar pseudopotential as the effective core potential . This basis set was obtained from the Basis Set Exchange website . Calculations for the zwitterionic form of cysteine were performed using the integral equation formalism of the polarizable continuum model (IEFPCM) with water used as the implicit solvent . This was performed to eliminate rearrangements of atoms leading to a neutral state, stable in vacuum.