Hybrid density functional theory calculations are performed for the first time to compare the stability, structural and electronic properties of monolayers and single-wall nanotubes based on pure Mo(W)S(Se)2 and mixed (Janus) Mo(W)SSe dichalcogenides.
The stability, structural and electronic properties of Mo and W dichalcogenide nanotubes have been compared at different wall compositions, chiralities and diameters using the same calculation scheme. Different types of mixed nanotubes are considered – with S or Se atoms on the outer (inner) shell of the nanotube. It was found that nanotubes Se(out)WS(in) with average diameter (Davr) greater than ≈40 Å have the negative strain energy.
Our calculations show that the band gap is direct for zigzag MS2 and S (out)MSe(in) nanotubes (M=Mo, W) but it becomes indirect in armchair nanotubes. For the MSe2 and Se(out) MS(in) nanotubes of both chiralities, the band gap is mostly direct, except the armchair tubes with Davr < 18 Å and zigzag tubes with Davr in interval from 18 to 26 Å where it is indirect.
[1] R.A. Evarestov, A.V. Kovalenko, A.V. Bandura, Physica E 115 (2020) 113681.
 will give a talk entitled “2D nanostructures based on pure Mo(W)S(Se)2 and mixed (Janus) Mo(W)SSe dichalcogenides: first principles study”.){kind=link}