A DFT study on the elastic and plastic properties of MoS2 nanosheet subjected to external electric field

• Density functional calculations for mechanical properties of MoS2 nanosheets.
• Prediction the Young's modulus and bulk's modulus of MoS2 nanosheets under various external electric fields.
• Investigation of plastic properties and critical strains of MoS2 nanosheets under various external electric fields.

Molybdenum disulfide (MoS2) may be synthesized in a large variety of forms such as particles, monolayer and multilayers nanosheets/nanotubes, ropes and ribbons. Due to such diversity, several applications can be found for MoS2. In this paper, on the basis of density functional theory (DFT) calculations using the generalized gradient approximation (GGA) with the Perdew− Burke−Ernzerhof (PBE) exchange correlation, the elastic properties including Young's and bulk moduli together with plastic properties of MoS2 nanosheet under external electric field with magnitudes within the range of 0 V/ang–1.5 V/ang are determined. It is demonstrated that up to the magnitude of 1 V/ang, the external electric field has a negligible influence on the bulk modulus of MoS2 nanosheet. However, by applying an external electric field equal to 1.3 V/ang, a significant increase in the value of bulk modulus occurs. Additionally, by applying an external electric field equal to 1.5 V/ang, the bulk modulus decreases suddenly, showing the considerable influence of high external electric field on the bulk modulus of MoS2 nanosheet. Also, it is observed that the first and second critical strains of the MoS2 nanosheet subjected to biaxial strain are smaller than those of the MoS2 nanosheet under uniaxial strain. Furthermore, it is revealed that for the both uniaxial and biaxial loading cases, by increasing the magnitude of external electric field, the stability of MoS2 nanosheet decreases.