2D nanostructures based on pure Mo(W)S(Se)2 and mixed (Janus) Mo(W)SSe dichalcogenides: first principles study

Latvijas Universitātes Cietvielu fizikas institūta zinātniskais seminārs 21. novembrī plkst. 11:00, LU CFI, Ķengaraga ielā 8, 2.stāva zālē Prof. Robert Evarestov (Quantum Chemistry Department, Saint Petersburg State University).

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.