A study of size-dependent properties of MoS2 monolayer nanoflakes using density-functional theory

Novel physical phenomena emerge in ultra-small sized nanomaterials. We study the limiting small-size-dependent properties of MoS$_{2}$ monolayer rhombic nanoflakes using density-functional theory on structures of size up to Mo$_{35}$S$_{70}$ (1.74~nm). We investigate the structural and electronic properties as functions of the lateral size of the nanoflakes, finding zigzag is the most stable edge configuration, and that increasing size is accompanied by greater stability. We also investigate passivation of the structures to explore realistic settings, finding increased HOMO-LUMO gaps and energetic stability. Understanding the size-dependent properties will inform efforts to engineer electronic structures at the nano-scale.