Theoretical prediction of disulfide defects (S₂^2-) in molybdenum disulfide monolayers

Defects have a noticeable influence on many properties of two-dimensional materials. The controlled formation of defects can be used for fine-tuning the electronic and chemical properties of transition metal dichalcogenide monolayers. The formation of a new type of displacement defect on the molybdenum disulfide (MoS₂) monolayer surface has been studied using density functional theory. In the defect structure, two sulfur atoms form a disulfide bridge between the Mo atoms. The sulfur-sulfur bond is confirmed by interatomic distances, atomic charges, and Electron Localization Function analysis.

The PBEsol density functional in the BAND2017 and VASP software packages was used for structural relaxation and NEB pathway calculations for the MoS₂ monolayers. The Slater-type orbital basis set TZP and PAW pseudopotential were used in the BAND2017 and VASP 6.2.0 codes, respectively. Additionally, single-point calculations with SCAN and HSE06 density functionals were performed. QTAIM charges and ELF distributions were calculated using the BAND2017 package.