Stacking effect on the orbital characters and transition probability of bilayer MoS2

Abstract

Abstract In this paper, employing the van der Waals (vdW) corrected density functional method, the electronic and optical properties of bilayer MoS2 are calculated for five different stacking patterns ( AA , AA ′ , AB ′ , AB , and A ′ B ). In this regard, the structural stability and the van der Waals interlayer distance are investigated. The minimum formation energy has indicated the overall trend of relative stability to be as AA ′ ≅ AB ≅ AB ′ ≫ AA ≅ A ′ B . This means AA ′ , AB ′ , and AB have the most and AA , and A ′ B have the least stable structures. The band structure and probability distribution for finding electrons in atomic orbitals have also been calculated in the Brillouin zone. The results obtained from band structures and orbital characters show the same trend in the three most stable and a different but the same trend for the two least stable orders. In addition, the oscillator strength has been derived from the calculation of the momentum operator matrix elements using first-principles methods. The calculation of transition probabilities from matrix elements indicates that AA ′ , AB , and AB ′ have higher transition probabilities than that of AA and A ′ B . The study of transition probability also shows the y-polarized light is stronger than the x-polarized light for all stacking patterns.