Theoretical Calculation And Analysis Of Transition Metal Dichalcogenides Represented By MoS₂ And WS₂

Since the discovery of graphene,two-dimensional materials have excellent physical,chemical,electronic and optical properties due to their unique two-dimensional layered structure,which can be widely used in optoelectronic devices,electrocatalysis,lithium ion batteries and solar cells.A large number of two-dimensional materials represented by hexagonal monoatomic layer boron nitride,triatomic transition metal dichalcogenides and layered double hydroxide have emerged,and the development of two-dimensional materials has been rapidly promoted.The transition metal dichalcogenides represented by MoS₂ and WS₂ is the research object.The material theory calculation software Materials Studio has different calculation module choices for different structures and materials that are for different calculation purposes.In this paper,CASTEP is used to calculate the relevant properties of MoS₂and WS₂.Materials Studio CASTEP is based on a quantum mechanical program that uses density functional theory?DFT?to simulate the solid,interface,and surface properties of various materials such as ceramics,semiconductors,and metals.And because the first principles are applied in the calculations,researchers are allowed to study the electronic,optical and physical properties of the structures without any experimental data input.In this paper,some transition metal dichalcogenides were synthesized experimentally.For better support experimental results,the two-dimensional nanomaterials represented by MoS₂ and WS₂ were modeled by Materials Studio,and were theoretically calculated by setting up the parameters.A single or three-layer energy band structure diagram and the density of states?DOS?curve of MoS₂ and WS₂ are obtained.Through the density of states?DOS?curve and the partial density of states?PDOS?curve,the distribution of the electronic states of the s,p,d and the contribution to the bonding can be analyzed,which lays a foundation for further theoretical analysis of the material in the next chapter.The nanosheets were prepared by doping the WS₂ and MoS₂.The model of WS₂doped with Mo atoms and MoS₂ doped with W atoms was constructed by using Materials Studio.The parameters were used to geometrically optimize the energy band structure and electronic density of states,and the data were obtained.The density of states?DOS?curve and partial density of states?PDOS?curve of MoS₂doped with W atoms and WS₂ doped with Mo atoms are obtained,and the curves calculated by compared with MS₂?M=Mo and W?in the same conditions,analyze the distribution of the electronic states of the s,p,d of the doped atoms and understand the contribution to the bonding.Then,when changing the cutoff energy of the plane wave,as the cutoff energy value increases,the band gap changes,and MS₂?M=Mo and W?changes with the cutoff energy.