Stacking Domains and Dislocation Networks in Marginally Twisted Bilayers of Transition Metal Dichalcogenides.

We apply a multiscale modeling approach to study lattice reconstruction in marginally twisted bilayers of transition metal dichalcogenides (TMD). For this, we develop density functional theory parametrized interpolation formulae for interlayer adhesion energies of MoSe_{2}, WSe_{2}, MoS_{2}, and WS_{2}, combine those with elasticity theory, and analyze the bilayer lattice relaxation into mesoscale domain structures. Paying particular attention to the inversion asymmetry of TMD monolayers, we show that 3R and 2H stacking domains, separated by a network of dislocations develop for twist angles θ^{∘}<θ_{P}^{∘}∼2.5° and θ^{∘}<θ_{AP}^{∘}∼1° for, respectively, bilayers with parallel (P) and antiparallel (AP) orientation of the monolayer unit cells and suggest how the domain structures would manifest itself in local probe scanning of marginally twisted P and AP bilayers.

Ab initio investigation of the electronic properties of graphene on InAs(111)A.

The equilibrium geometry and electronic structure of graphene on the most stable In-vacancy InAs(111)A surface has been investigated using the density functional and pseudopotential theories. The equilibrium distance between graphene and InAs(111) is found to be 3.05 Å with adsorption energy approximately 38 meV/C atom. According to our electronic band calculation, there is a re-distribution of the charge density around the graphene sheet, which leads to the development of a dipole moment along the surface normal. Scanning tunnelling microscopy image simulations suggest that the InAs(111) substrate is visible through the graphene layer.